A multi-day excessive heat event occurred across much of the mid-Atlantic from August 11-13, 2021. Temperatures in the mid to upper 90s combined with dew point values near 70 caused widespread heat index values near to above 105F on both August 11 and 12, and locally into the 13th before a cold front brought relief.
Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS PHI wrote it up.
A multi-day excessive heat event occurred across much of the mid-Atlantic from August 11-13, 2021. Temperatures in the mid to upper 90s combined with dew point values near 70 caused widespread heat index values near to above 105F on both August 11 and 12, and locally into the 13th before a cold front brought relief.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Philadelphia/Mount Holly wrote its last area forecast discussion before the first event at Aug 11, 5:23 AM EST, 3 hours 37 minutes earlier.
Area Forecast Discussion
National Weather Service Mount Holly NJ
623 AM EDT Wed Aug 11 2021
.SYNOPSIS...
Bermuda high pressure will continue to influence our weather
into Friday. A cold front approaching from the northwest is
forecast to arrive on Saturday. The frontal system is
anticipated to stall to the south of our region for Sunday into
the early part of the new week as high pressure builds across
New York and New England.
&&
.NEAR TERM /THROUGH TONIGHT/...
Excessively hot and humid conditions ramp up today and will
continue through Friday.
Daybreak forecast update...Some pesky moderate to heavy showers
have persisted across the southern Poconos and portions of
northwest New Jersey early this morning, however this activity
should continue to wane and move toward the Hudson Valley
through mid-morning.
A weak mid-level wave which caused the convection Tuesday
afternoon and evening will continue to push away from the area
today. Meanwhile, a low amplitude mid-level trough will dig
slowly southeastward from the upper Midwest toward the Great
Lakes region through tonight and close off over the Hudson Bay
as it does so. Southwesterly return flow will result today and
continue through the end of the week with subtropical ridging
extending from the western Atlantic into the Southeast and
strong low pressure across Hudson Bay.
A mid-level perturbation associated with convection across the
Midwest Tuesday and surface troughing developing from
central/southeastern Pennsylvania into the upper Delaware River
Valley should be enough to initiate some showers and
thunderstorms this afternoon. There is a little uncertainty to
the coverage and intensity of the storms, but the CAM guidance
seems to support a broken line of convection moving into the
area later on this afternoon then dissipating into the evening
as instability wanes. Some isolated damaging winds may be
possible with the stronger or more organized cells, but
widespread severe convection is not anticipated.
The main story however remains the expected extended period of
excessive heat and humidity starting ramping up today and
lasting through Friday. Temperatures and dewpoints are forecast
to rise quickly after daybreak amid the southwesterly surface
flow with highs in the low to mid 90s by this afternoon and
dewpoints in the low to mid 70s. Resulting heat index values
should climb above 100 degrees away from the coasts and higher
terrain and some areas, mainly across the urban corridor and
Delmarva region, are expected to reach or exceed 105 degrees.
There won't be much relief tonight with lows in the low to mid
70s for most, but this will depend on the evolution of the
afternoon showers and storms. The lack of any low-level dry air
leads me to believe there won't be much in the way of dewpoints
mixing out unfortunately.
As of this update, the previously issued heat headlines remain
largely the same, however we have upgraded portions of the
previously issued Heat Advisory to an Excessive Heat Warning
across the I-78 corridor and Warren County, NJ. In addition,
we've also added inland Cape May NJ to the Heat Advisory. This
is due to increased confidence of heat index values exceeding
105 degrees for the majority of these areas with more details
in the "Short Term" discussion section.
&&
.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
The low amplitude trough axis will remain to our northwest
Thursday with subtropical ridging in place across the western
Atlantic and Southeast. Another mid-level wave will approach the
northern portion of the area from the southern Great Lakes.
The prolonged period of excessive heat and humid conditions
will continue and likely reach its most oppressive peak on
Thursday. The flow will become slightly more westerly,
introducing more subsidence than will be in place Wednesday. As
a result, temperatures are expected to climb a few degrees
higher with maximum afternoon temperatures in to mid to upper
90s forecast. This combined with the continued southwesterly
surface flow and low to mid 70s dewpoints will lead to
widespread heat index values of 105-110 degrees for most of the
forecast area, including the I-95 and I-78 corridors, Delmarva,
and southern NJ.
Convection appears probable upstream of the region associated
with the aforementioned mid-level wave and instability should be
a bit higher on Thursday (MLCAPE ~>3000 J/kg). However, there
will be more subsidence acting against convective initiation
locally. If convection is able to initiate or hold together into
the area, it will likely be severe, but thinking we'll have
enough subsidence to preclude mention of chance PoPs during the
afternoon and early evening hours. As the jet axis resulting in
the local subsidence pivots northeast, there may be a window of
opportunity for convection into the late evening hours, mainly
for the northern half of the area.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
Friday represents a challenging forecast as temps/dewpoints will
all be highly dependent on the advancing prefrontal trough
associated with an upstream cold front. Much of the guidance
suggests that convection associated with the prefrontal trough
should start to impact portions of the Lehigh Valley/Poconos by
early afternoon. However the convection doesn't appear likely
to impact the rest of the forecast region until late overnight
into Saturday. With another day of overnight lows struggling to
reach the 70s Thursday night and very efficient mixing (low
level lapse rates in excess of 10C from the GFS and NAM) temps
will likely surge back into the mid to upper 90s. Several of the
operational models are indicating high 90s for much of the
region and with 21C at 850mb its quite possible. With dew
points still in the low to mid 70s, that would lead to another
round of Heat Advisories and Excessive Heat Warnings. Given the
uncertainty in the locations that may be impacted by
convection, we opted to not extend current headlines through
Friday but we feel fairly certain that at least some locations
will need heat hazard headlines.
With the abundant instability, moisture, and a form of lift from
the advancing prefrontal trough, we will see the potential for
some strong to severe thunderstorms developing in the afternoon
Friday generally from the Delaware Valley to areas north and
west. Shear isn't incredibly strong and the best dynamics are
upstream rather than over our region. Thus storms look to be
outflow dominate leading to the main threat for the region being
damaging winds.
Heading into the weekend the cold front finally arrives Saturday
with highs still in the upper 80s to low 90s. Saturday night
should feel amazing across the region as a break from the high
heat and humidity. Dewpoints drop into the mid 50s to low 60s
with overnight lows in the mid 60s. That will offer quite the
break from this week's oppressive conditions.
The cold front should then stall south of the region as high
pressure returns for the region. This will lead to around round
of summer type diurnally driven showers mainly across DelMarVa
and southern NJ with temps starting next week a few degrees
below normal.
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
Today...Some patchy sub-VFR fog is possible through around 12Z,
otherwise prevailing VFR. A broken line of showers and
thunderstorms appears probable to affect the PHL area terminals
and north between roughly 20Z-00Z. Winds southwesterly around
5-10 kts. High confidence overall.
Tonight...VFR. South to southwesterly winds 5 kts or less. High
confidence.
Outlook...
Thursday...VFR. Southwesterly winds 5-10 kts during the day and 5
kts or less at night. High confidence.
Friday...Early morning low clouds and visibility restrictions
are possible, otherwise mainly VFR. A chance of afternoon and
evening showers and thunderstorms. Southwest around 10 knots.
Moderate confidence.
Saturday...Early morning low clouds and visibility restrictions
are possible, otherwise mainly VFR. A frontal system moving
through the day will likely bring at least a period of lower
flight restrictions due to showers and thunderstorms. Southwest
to west around 10 knots. Moderate confidence.
Sunday...Generally VFR. North to northeast wind 5 to 10 knots.
Moderate confidence.
&&
.MARINE...
Sub-advisory conditions. South to southwesterly winds 10-15 kts with
some gusts up to 20 kts possible during the daytime hours. Seas
mainly 2-3 feet.
Outlook...
Thursday...Sub-advisory conditions. South to southwesterly winds 10-
15 kts with some gusts up to 20 kts possible during the daytime
hours. Seas mainly 2-3 feet.
Friday through Sunday...No marine headlines are anticipated.
Rip currents...
There is a low risk of rip currents through Thursday.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Excessive Heat Warning from noon today to 8 PM EDT Thursday
for PAZ060>062-070-071-101>106.
Heat Advisory from noon today to 8 PM EDT Thursday for PAZ054-
055.
NJ...Excessive Heat Warning from noon today to 8 PM EDT Thursday
for NJZ007>010-012-013-015-017>020-027.
Heat Advisory from noon today to 8 PM EDT Thursday for NJZ001-
014-016-021>023-026.
DE...Excessive Heat Warning from noon today to 8 PM EDT Thursday
for DEZ001.
Heat Advisory from noon today to 8 PM EDT Thursday for DEZ002-
003.
MD...Heat Advisory from noon today to 8 PM EDT Thursday for MDZ012-
015-019-020.
MARINE...None.
&&
Synopsis...Deal
Near Term...Staarmann
Short Term...Staarmann
Long Term...Deal
Aviation...Deal/Staarmann
Marine...Deal/StaarmannHazardous Weather Outlook National Weather Service Mount Holly NJ 0503 AM EDT Wed Aug 11 2021 DEZ001-120903- New Castle- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for New Castle County in Delaware. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. DEZ002-120903- Kent- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Kent County in Delaware. .DAY ONE...Through tonight. Hot conditions could result in heat exhaustion with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Hot conditions could result in heat exhaustion with prolonged exposure on Thursday. Hot conditions could result in heat exhaustion with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. DEZ003-120903- Inland Sussex- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for inland portions of Sussex County in Delaware. .DAY ONE...Through tonight. Hot conditions could result in heat exhaustion with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Hot conditions could result in heat exhaustion with prolonged exposure on Thursday. Hot conditions could result in heat exhaustion with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. DEZ004-120903- Delaware Beaches- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for the Atlantic coastal portions of Sussex County in Delaware. .DAY ONE...Through tonight. There is a low probability of widespread hazardous weather. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Hot conditions could result in heat exhaustion with prolonged exposure on Thursday. Hot conditions could result in heat exhaustion with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ054-120903- Carbon- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Carbon County in Pennsylvania. .DAY ONE...Through tonight. Hot conditions could result in heat exhaustion with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Hot conditions could result in heat exhaustion with prolonged exposure on Thursday. Hot conditions could result in heat exhaustion with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ055-120903- Monroe- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Monroe County in Pennsylvania. .DAY ONE...Through tonight. Hot conditions could result in heat exhaustion with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Hot conditions could result in heat exhaustion with prolonged exposure on Thursday. Hot conditions could result in heat exhaustion with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ060-120903- Berks- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Berks County in Pennsylvania. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ061-120903- Lehigh- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Lehigh County in Pennsylvania. .DAY ONE...Through tonight. Hot conditions could result in heat exhaustion with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Hot conditions could result in heat exhaustion with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ062-120903- Northampton- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Northampton County in Pennsylvania. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ070-120903- Delaware- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Delaware County in Pennsylvania. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ071-120903- Philadelphia- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Philadelphia County in Pennsylvania. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ101-120903- Western Chester- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for western Chester County in Pennsylvania. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ102-120903- Eastern Chester- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for eastern Chester County in Pennsylvania. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ103-120903- Western Montgomery- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for western Montgomery County in Pennsylvania. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ104-120903- Eastern Montgomery- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for eastern Montgomery County in Pennsylvania. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ105-120903- Upper Bucks- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for upper Bucks County in Pennsylvania. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. PAZ106-120903- Lower Bucks- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for lower Bucks County in Pennsylvania. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could quickly result in heat exhaustion or heat stroke on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ001-120903- Sussex- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Sussex County in New Jersey. .DAY ONE...Through tonight. Hot conditions could result in heat exhaustion with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Hot conditions could result in heat exhaustion with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ007-120903- Warren- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Warren County in New Jersey. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ008-120903- Morris- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Morris County in New Jersey. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ009-120903- Hunterdon- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Hunterdon County in New Jersey. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could quickly result in heat exhaustion or heat stroke on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ010-120903- Somerset- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Somerset County in New Jersey. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could quickly result in heat exhaustion or heat stroke on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ012-120903- Middlesex- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Middlesex County in New Jersey. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could quickly result in heat exhaustion or heat stroke on Thursday. Dangerously hot conditions could quickly result in heat exhaustion or heat stroke on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ013-120903- Western Monmouth- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for western Monmouth County in New Jersey. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ014-120903- Eastern Monmouth- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for eastern Monmouth County in New Jersey. .DAY ONE...Through tonight. Hot conditions could result in heat exhaustion with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Hot conditions could result in heat exhaustion with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ015-120903- Mercer- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Mercer County in New Jersey. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could quickly result in heat exhaustion or heat stroke on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ016-120903- Salem- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Salem County in New Jersey. .DAY ONE...Through tonight. Hot conditions could result in heat exhaustion with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Hot conditions could result in heat exhaustion with prolonged exposure on Thursday. Hot conditions could result in heat exhaustion with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ017-120903- Gloucester- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Gloucester County in New Jersey. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Dangerously hot conditions could quickly result in heat exhaustion or heat stroke on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ018-120903- Camden- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Camden County in New Jersey. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ019-120903- Northwestern Burlington- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for northwestern Burlington County in New Jersey. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ020-120903- Ocean- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for inland portions of Ocean County in New Jersey. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ021-120903- Cumberland- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Cumberland County in New Jersey. .DAY ONE...Through tonight. Hot conditions could result in heat exhaustion with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Hot conditions could result in heat exhaustion with prolonged exposure on Thursday. Hot conditions could result in heat exhaustion with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ022-120903- Atlantic- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for inland portions of Atlantic County in New Jersey. .DAY ONE...Through tonight. Hot conditions could result in heat exhaustion with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Hot conditions could result in heat exhaustion with prolonged exposure on Thursday. Hot conditions could result in heat exhaustion with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ023-120903- Cape May- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Cape May County excluding the Atlantic coast in New Jersey. .DAY ONE...Through tonight. There is a low probability of widespread hazardous weather. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Hot conditions could result in heat exhaustion with prolonged exposure on Thursday. Hot conditions could result in heat exhaustion with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ024-120903- Atlantic Coastal Cape May- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for the Atlantic coastal portions of Cape May County in New Jersey. .DAY ONE...Through tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ025-120903- Coastal Atlantic- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for coastal portions of Atlantic County in New Jersey. .DAY ONE...Through tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ026-120903- Coastal Ocean- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for coastal portions of Ocean County in New Jersey. .DAY ONE...Through tonight. Hot conditions could result in heat exhaustion with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Hot conditions could result in heat exhaustion with prolonged exposure on Thursday. Hot conditions could result in heat exhaustion with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. NJZ027-120903- Southeastern Burlington- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for southeastern Burlington County in New Jersey. .DAY ONE...Through tonight. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. MDZ012-120903- Kent MD- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Kent County in Maryland. .DAY ONE...Through tonight. Hot conditions could result in heat exhaustion with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Hot conditions could result in heat exhaustion with prolonged exposure on Thursday. Hot conditions could result in heat exhaustion with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. MDZ015-120903- Queen Annes- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Queen Annes County in Maryland. .DAY ONE...Through tonight. Hot conditions could result in heat exhaustion with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Hot conditions could result in heat exhaustion with prolonged exposure on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. MDZ019-120903- Talbot- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Talbot County in Maryland. .DAY ONE...Through tonight. Hot conditions could result in heat exhaustion with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Hot conditions could result in heat exhaustion with prolonged exposure on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. MDZ020-120903- Caroline- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for Caroline County in Maryland. .DAY ONE...Through tonight. Hot conditions could result in heat exhaustion with prolonged exposure. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. Hot conditions could result in heat exhaustion with prolonged exposure on Thursday. Dangerously hot conditions could result in heat exhaustion or heat stroke with prolonged exposure on Friday. Please go to weather.gov/phi/ehwo for more information on potential weather hazards. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. ANZ430-120903- Delaware Bay waters north of East Point NJ to Slaughter Beach DE- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for upper Delaware Bay. .DAY ONE...Through tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. ANZ431-120903- Delaware Bay waters south of East Point NJ to Slaughter Beach DE- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for lower Delaware Bay. .DAY ONE...Through tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. ANZ450-120903- Coastal waters from Sandy Hook to Manasquan Inlet NJ out 20 nm- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for the Atlantic coastal waters adjacent to Monmouth County out 20 nm. .DAY ONE...Through tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. ANZ451-120903- Coastal waters from Manasquan Inlet to Little Egg Inlet NJ out 20 nm- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for the Atlantic coastal waters adjacent to Ocean County out 20 nm. .DAY ONE...Through tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. ANZ452-120903- Coastal waters from Little Egg Inlet to Great Egg Inlet NJ out 20 nm- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for the Atlantic coastal waters adjacent to Atlantic County out 20 nm. .DAY ONE...Through tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. ANZ453-120903- Coastal waters from Great Egg Inlet to Cape May NJ out 20 nm- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for the Atlantic coastal waters adjacent to Cape May County out 20 nm. .DAY ONE...Through tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. ANZ454-120903- Coastal waters from Cape May NJ to Cape Henlopen DE out 20 nm- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for the Atlantic coastal waters adjacent to the mouth of Delaware Bay out 20 nm. .DAY ONE...Through tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. ANZ455-120903- Coastal waters from Cape Henlopen to Fenwick Island DE out 20 nm- 0503 AM EDT Wed Aug 11 2021 This Hazardous Weather Outlook is for the Atlantic coastal waters adjacent to Sussex County out 20 nm. .DAY ONE...Through tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures.
The national radar mosaic for the moment the first event began.
1 excessive heat. Local standard time, as filed.
Widespread heat index values in excess of 110F occurred on August 11, 12, and 13.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Maryland in 2021Every state in 2021This day in weather historyWarnings in Maryland, August 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 987499.