The end of June marked the beginning of a prolonged period of extreme heat across much of southeast Michigan. This heat wave continued into early July.
Every event with a place to put it; 13 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 DTX wrote it up.
The end of June marked the beginning of a prolonged period of extreme heat across much of southeast Michigan. This heat wave continued into early July. Most areas saw heat index values climb to around or above 105 with little to no relief during the overnight hours. For some locations, overnight heat index values remained around or above 80 degrees. While heat index values may not have reached 105 for 3 hours on June 30th, this was the first day of a heat wave that brought a prolonged period of extreme heat with little to no relief during the overnight hours.
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 Detroit, MI wrote its last area forecast discussion before the first event at Jun 30, 5:05 AM EST, 5 hours 55 minutes earlier. Its key messages:
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
605 AM EDT Tue Jun 30 2026
.KEY MESSAGES...
- An Extreme Heat Warning is in effect Tuesday afternoon through
Thursday for high temperatures reaching the mid 90s to 100 degrees
and heat indices in excess of 105 degrees each day.
- There will be little nighttime relief as lows only cool into the
mid 70s with heat index around 80 each night.
- Wednesday and Thursday are the hottest days, however hot and humid
conditions also extend into Friday and the holiday weekend along
with increasing potential for showers and thunderstorms.
&&
.AVIATION...
Strong influence of a large high pressure system centered over the
Ohio valley will maintain a high degree of stability across the
region through tonight. This ensures widespread VFR conditions, with
a limited coverage of high based cumulus expected. A period of
thicker mid level cloud will be possible at times, particularly at
MBS, as convection lifts out of the upper Miss valley and toward
northern lower. Prevailing winds from the southwest, turning
modestly gusty during the afternoon.
D21/DTW Convection... No thunderstorms are forecast for the D21
airspace through Tuesday night.
.DTW THRESHOLD PROBABILITIES...
* None
&&
.PREV DISCUSSION...
Issued at 250 AM EDT Tue Jun 30 2026
DISCUSSION...
Southeast Michigan now resides securely on the northern periphery of
a sizable heat dome, as the large-scale pattern remains governed by
a sprawling 594 to 596 dam subtropical ridge centered over the Ohio
Valley region. Increasing depth and magnitude to southwest flow
around the western flank of the ridge axis effectively encasing the
region within a high magnitude thermal and moisture profile, as
evident by a projected 850 mb temperature of 23-25c and a dewpoint
encroaching on mid 70s at times. Net result remains a prolonged
extreme heat event featuring near-record temperatures that gets
underway today and persists through at least Thursday. An extreme
heat warning is now active across the region for this window.
Ambient afternoon highs will consistently surge into the mid-to-
upper 90s, with a few locations testing the 100F mark. Combined with
the elevated dewpoint, peak heat index values are forecast to range
between 105 and 110F. Virtually no overnight relief anticipated
within this environment as minimum temperatures struggle to drop
below the mid-to-upper 70s. Risk for organized convective
development remains very low across this period, given the highly
capped environment and unfavorable positioning to witness convection
growing upscale out of the Dakotas and upper MS valley and across
the ridge periphery. A limited opportunity could emerge Wednesday
across the Saginaw valley and thumb, with a subset of the model
solution space initiating convection across northern lower during
this time.
By Friday into the weekend, medium-range deterministic and ensemble
guidance continue to suggest the long wave pattern will undergo a
more notable shift. As the steering flow becomes more zonal along
the international border, successive shortwaves rounding the
northern periphery will gradually, yet effectively dampen, broaden
and suppress the ridge axis into the Ohio valley. Potential for heat
and humidity to remain elevated at least into Friday with the
resident airmass slow to dislodge, before the downgrade in upper
heights combined with increased convective potential likely yields
more typical warmth and humidity for the holiday weekend. A more
receptive underlying environment will exist now for convective
development, but with the usual uncertainty at this time range
regarding potential timing and scale with strong dependence on the
mesoscale evolution upstream. Further refinement of precipitation
chances are likely.
MARINE...
Wind gradually veers to southwest today, allowing a warm front to
advance across Lake Huron today. As the hot and humid air mass
builds in, the gradient will maintain SW wind of 10 to 15 kt today
through Thursday, with gusts generally capped around 20 kt due to
increased stability over the relatively cooler water. There will be
a chance for thunderstorms over Lake Huron today as the front lifts
through, but confidence is low on timing. Areas of fog may develop
over the cooler open waters as well. Additional storms Wednesday and
Thursday will be most likely to occur near northern Lake Huron where
the prevailing storm track will set up along the edge of the more
stable air to the south.
CLIMATE...
Daily Records for the Upcoming Week...
Detroit
Record High Record Warm Minimum
Tue June 30 96 (1931) 76 (2018)
Wed July 1 98 (1931) 80 (1931)
Thu July 2 99 (2011) 76 (2018)
Fri July 3 100 (1911) 78 (1911)
Sat July 4 102 (2012) 79 (1921)
Flint
Record High Record Warm Minimum
Tue June 30 98 (1933) 76 (2018)
Wed July 1 102 (1931) 72 (2018)
Thu July 2 100 (1931) 73 (2002)
Fri July 3 99 (1921) 73 (1983)
Sat July 4 102 (1921) 76 (1999)
Saginaw
Record High Record Warm Minimum
Tue June 30 99 (1964) 77 (2018)
Wed July 1 103 (1931) 78 (1931)
Thu July 2 100 (1931) 73 (2002)
Fri July 3 99 (1966) 76 (1974)
Sat July 4 97 (2012) 75 (2012)
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Extreme Heat Warning from noon today to 8 PM EDT Thursday for
MIZ047>049-053>055-060>063-068>070-075-076-082-083.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&
AVIATION.....MR
DISCUSSION...MR
MARINE.......TF
CLIMATE......MV
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.Hazardous Weather Outlook National Weather Service Detroit/Pontiac MI 311 AM EDT Tue Jun 30 2026 MIZ047>049-053>055-060>063-068>070-075-076-082-083-010715- Midland-Bay-Huron-Saginaw-Tuscola-Sanilac-Shiawassee-Genesee-Lapeer- St. Clair-Livingston-Oakland-Macomb-Washtenaw-Wayne-Lenawee-Monroe- 311 AM EDT Tue Jun 30 2026 This hazardous weather outlook is for southeast Michigan. .DAY ONE...Today and Tonight An Extreme Heat Warning is in effect this afternoon through tonight. Refer to the latest weather message for additional detail. .DAYS TWO THROUGH SEVEN...Wednesday through Monday An Extreme Heat Warning remains in effect Wednesday through Thursday evening. Refer to the latest weather message for additional detail. Hot and humid conditions will persist Friday and potentially into the upcoming weekend. Thunderstorm chances begin to increase during this time. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed today and tonight. LCZ460-LEZ444-LHZ361>363-421-422-441>443-462>464-010715- Lake St Clair- Michigan Waters of Lake Erie from Detroit River to North Cape MI- Lake Huron from 5NM east of Mackinac Bridge to Presque Isle Lt beyond 5 NM off shore- Lake Huron from Presque Isle Light to Sturgeon Point MI beyond 5NM off shore- Lake Huron from Sturgeon Point to Alabaster MI beyond 5NM off shore- Outer Saginaw Bay SW of Alabaster to Port Austin MI to Inner Saginaw Bay-Inner Saginaw Bay SW of Point Au Gres to Bay Port MI- Port Austin to Harbor Beach MI-Harbor Beach to Port Sanilac MI- Port Sanilac to Port Huron MI- Lake Huron from Port Austin to Harbor Beach beyond 5NM Off Shore- Lake Huron from Harbor Beach to Port Sanilac beyond 5NM Off Shore- Lake Huron from Port Sanilac to Port Huron beyond 5NM Off Shore- 311 AM EDT Tue Jun 30 2026 This hazardous weather outlook is for portions of Lake Erie, Lake Huron and Lake St Clair. .DAY ONE...Today and Tonight No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Wednesday through Monday A chance of thunderstorms will exist across mainly northern lake Huron Wednesday and Thursday. Increasing potential across all marine areas Friday into the upcoming weekend. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed today and tonight. You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit. MR
The national radar mosaic for the moment the first event began.
13 excessive heat. Local standard time, as filed.
During the afternoon and evening hours on June 30th, the observation from Flint (KFNT) had heat index values reach 100 to 103.
Monroe AWOS (KTTF) observed heat index values between 100 degrees and 108 degrees on June 30th. That night, heat index values remained above 80 degrees.
During the afternoon and evening hours on June 30th, the observation from the Troy (KVLL) and Pontiac (KPTK) airports observed heat index values of 100 to 103. That night, heat index values remained at or above 85 degrees.
During the afternoon and evening hours on June 30th, the observation from Lapeer (KD59) had heat index values reach 105 for numerous hours. Heat index values did not fall below 85 that night.
During the afternoon and evening hours, heat index values at Tuscola reached 100 to 105 degrees. Overnight heat index values of 85 to 85 degrees were also observed.
During the afternoon and evening hours on June 30th, the observation from the Selfridge Air National Guard Base (KMTC) observed heat index values of 100 to 105. That night, heat index values remained above 85 degrees.
During the afternoon and evening hours, heat index values at Owosso reached 100 to 105 degrees. While the heat index did not reach 105 for 3 hours, overnight heat index values never fall below 85 degrees.
During the afternoon and evening hours, heat index values at Bad Axe reached 100 to 103 degrees.
Adrian ASOS (KADG) observed heat index values between 100 degrees and 101 degrees on the afternoon and evening of June 30. That night, heat index values remained above 80 degrees.
During the afternoon and evening hours on June 30th, the Detroit Willow Run Airport (KYIP) observed heat index values of 100 to 103. That night, heat index values remained above 80 degrees.
During the afternoon and evening hours, heat index values in Midland reached 100 to 103 degrees. Overnight heat index values did not fall below 85 degrees were also observed.
During the afternoon and evening hours, heat index values at the Saginaw Airport (KMBS) reached 100 to 103 degrees. Overnight heat index values of 80 to 85 degrees were also observed.
During the afternoon and evening hours on June 30th, the following observation sites observed heat index values of 100 degrees or higher: Grosse Isle AWOS (KONZ), Detroit C Young Airport ASOS (KDET), and the Detroit Metro Airport (KDTW). Grosse Isle AWOS had a number of hours with heat index values of 105. That night, heat index values remained above 80 degrees.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Michigan in 2026Every state in 2026This day in weather historyWarnings in Michigan, June 2026
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: 1357030, 1357011, 1357028, 1357029, 1357034, 1357020, 1357032, 1357033, 1357013, 1357018, 1357036, 1357035, 1357016.