A strong ridge of high pressure encompassed the Western CONUS from September 1st through 8th, leading to anomalously hot temperatures along the California coast, and even more extreme temperatures in interior valleys and all mountain zones, where very hot daytime temperatures combined with a lack of overnight cooling created extreme heat risk . Excessive Heat Warnings were issued for interior…
Every event with a place to put it; 25 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 MTR wrote it up.
A strong ridge of high pressure encompassed the Western CONUS from September 1st through 8th, leading to anomalously hot temperatures along the California coast, and even more extreme temperatures in interior valleys and all mountain zones, where very hot daytime temperatures combined with a lack of overnight cooling created extreme heat risk . Excessive Heat Warnings were issued for interior areas and mountains of Monterey/San Benito Counties for the period September 1st through 8th, and for interior valleys and mountain zones around the San Francisco Bay Area from September 4th through 8th. A combination of Heat Advisories and an Excessive Heat Warning was issued for parts of Monterey Bay and its near coastal valleys, the San Francisco Bay Shoreline, and Marin Coastal Mountains from September 4th through 8th, along with a Heat Advisory for the Central Coast, San Francisco, and coastal North Bay on September 6th. Several daily record high temperature records were shattered, along with a handful of monthly and all-time records. Triple digit temperatures were reported across a vast swath of the interior, with some sites reaching 110 degrees and higher. Reports of power outages, heat related illnesses and deaths were received. Counties opened/operated one or more cooling centers to provide relief from the heat.
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 San Francisco Bay Area, CA wrote its last area forecast discussion before the first event at Sep 4, 8:24 AM PST, 36 minutes earlier.
Area Forecast Discussion
National Weather Service San Francisco Bay Area
924 AM PDT Sun Sep 4 2022
...Dangerous Heat Through Early Next Week...
.SYNOPSIS...An extended period of dangerous heat is expected
across the interior through at least the middle of the upcoming
week. Many far inland locations are likely to exceed 100 degrees
each afternoon through midweek. Meanwhile, the heat will be
tempered near the coast, but temperatures will still be well above
normal.
&&
.DISCUSSION...as of 09:24 AM PDT Sunday...The heat is on. Today is
the first day where widespread dangerous heat will impact the Bay
Area and Central Coast. Morning satellite shows skies are
crystal clear over our CWA with a small patch of clouds near the
Farallon Islands and the tip of Point Reyes. Temperatures this
morning are rather impressive, especially in the hills. The last
few mornings have been mild in the hills, but this morning we're
seeing more 80s with a few right around 90 degrees. This
definitely makes sense after looking at the KOAK sounding from
this morning. The 850mb temp was 29C, which sets a daily record.
No updates to the ongoing forecast. See more details below.
Two other items of note that we'll be watching closely with the
afternoon forecast will be: How long the heat will last and
chances of precip next weekend.
A few takeaways for the heat:
* Going to the beach? Try to pick one with a lifeguard.
* Avoid outdoor activities during the hottest portion of the day.
* Stay hydrated and take frequent cooling breaks in the shade.
* Check on relatives, neighbors and friends who may not have access
to adequate cooling.
* Never leave the elderly, children or pets in unattended vehicles.
* Use air conditioning where possible.
&&
.PREV DISCUSSION...as of 03:30 AM PDT Sunday...Forecast confidence
continues to increase with respect to several days of dangerous
heat across the region's interior from today through the middle of
the upcoming work week. Heat Risk will range from high to very
high across just about all inland areas. This is especially so on
Monday and Tuesday with widespread triple digit heat likely away
from the coast with the region's warmest interior locations
approaching or exceeding 110 deg F. In addition to the oppressive
heat each afternoon, overnight temperatures will only cool into
the upper 70s to mid 80s in the region's higher terrain with the
far interior valleys only cooling into the mid 60s to lower 70s.
Still expecting some relief near the coast as a very shallow
marine layer and onshore flow is likely to persist. That said,
there is a growing concern for temperatures to reach the upper 80s
to even lower 90s in coastal areas by Monday and Tuesday as the
very hot air mass aloft mixes down to the surface. While some
cooling is possible on Wednesday, the interior heat is likely to
persist with the mid/upper level ridge locked in place. As such,
the Heat Advisory and Excessive Heat Warning have been extended
another 24 hours into Tuesday and Wednesday respectively. As the
situation evolves in the days ahead, heat products may need to be
extended to the coast.
The deterministic and ensemble guidance indicates slight weakening
of the ridge aloft at some point Wednesday, yet hold the strong
ridge in place potentially into the end of the upcoming week. If
this holds true, our interior valley locations could see 5 or more
days of triple digit heat. This will need to be closely monitored in
the days ahead as the region's heat events are normally short lived
while this one appears to be prolonged. This of course increases the
risk of heat-related illnesses.
In the extended, the mid/upper level high pressure resulting in the
ongoing heat wave will begin to weaken and shift inland by the
upcoming weekend. This would result in a gradual cooling trend
across the entire region. Additionally, both deterministic and
ensemble guidance suggest tropical moisture advecting northward into
the Desert Southwest and even southern/central California next
weekend. Details vary greatly this far out in time, but impacts
could be great if we were to get any convection following the
prolonged period of dry and very hot conditions. Something else on
our radar so-to-speak as we move forward in time.
&&
.AVIATION...as of 04:31 AM PDT Sunday...For the 12Z TAFs. Stratus
is trying to build out over the ocean, but it remains over 100
miles out to sea. High pressure building creates clear, VFR skies
over the region that will last through the TAF period. Winds will
be light and onshore, except for when the seabreeze develops
Sunday afternoon.
Vicinity of KSFO...VFR. Breezy onshore winds. Slight chance for
gusts through the San Bruno gap around 20 knots for a couple hours
Sunday afternoon.
KSFO Bridge Approach...Similar to SFO.
Monterey Bay...Light winds become breezy Sunday afternoon. VFR
through the TAF period.
&&
.FIRE WEATHER...as of 03:30 AM PDT Sunday...Strong high pressure
over the region will continue to strengthen resulting in very hot
and dry conditions across the interior through much of the
upcoming week. Meanwhile, a shallow marine layer will keep
conditions slightly cooler near the coast along with higher
humidity, especially during the overnight hours. While breezy
terrain driven winds are possible in the coastal gaps and over the
ridges each afternoon, widespread strong winds are not
anticipated. However, very low humidity and dry fuels will lead to
enhanced fire weather concerns through the forecast period.
&&
.MARINE...as of 02:35 AM PDT Sunday...Prevailing northwest winds
to create squared seas through steep wind waves between 6 to 8
feet at 7 to 8 seconds while a moderate period southerly swell
persists in the background. The seas for Sunday will be hazardous
for smaller craft vessels. While winds are forecast to diminish
after Labor Day for the southern waters, winds will remain breezy
over the northern waters.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...SCA...Pt Arena to Pt Piedras Blancas 0-10 nm through 9 AM
SCA...Pt Arena to Pt Piedras Blancas 10-60 nm through 3 PM
Excessive Heat Warning...CAZ503-504-506-510-512>518
Heat Advisory...CAZ502-508-528-529
&&
PUBLIC FORECAST: SO/RGass
AVIATION: DK
MARINE: DK
FIRE WEATHER: RGass
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www.youtube.com/nwsbayareaThe national radar mosaic for the moment the first event began.
25 heat. Local standard time, as filed.
Public libraries were used as cooling shelters throughout the county. Cost of operating libraries beyond normal business hours was $1732.04.
Forty cooling centers opened in Alameda County Bay Shoreline communities.
Six cooling sites opened in Alameda interior valley communities.
Two libraries were used as cooling shelters and a third building was opened as a cooling shelter during the event. $300 total was spent by cities and the county to provide bottled water. No fatalities reported.
Four calls received by EMS for heat-related illness. Of those, three were low-priority and one was Code 3 (emergency).
Santa Clara County EMS reported 60 calls were received for heat-related illness.
A daily record high temperature of 107 deg was set at the Gilroy Coop site, breaking the previous record 103 deg set in 1998. Various other stations reported temperatures in the upper 90s to mid 100s throughout the valley.
King City coop site tied its daily record of 104 deg set in 1975. Bradley RAWS reported a high temperature of 111 degrees. Various other unofficial sites reported high temperatures between 105 and 111 degrees.
Pinnacles NP reported a max temperature of 111 degrees. Several other unofficial sites in the surrounding mountains reported high temperatures between 102 and 108 degrees.
Arroyo Seco RAWS reported a max temperature of 111 deg. Various other unofficial sites in the surrounding mountains reported temperatures between 101 and 108 deg.
Hollister ASOS reported a max temperature of 106 deg. Carmel Valley coop site reported a max temperature 101 deg. Other unofficial sites in the vicinity reported max temperatures in the upper 90s to 104 deg.
Livermore Coop site set an all time record of 116 deg., breaking the previous all time record of 115 deg. set in 1950. Livermore ASOS reported a max temperature of 113 degrees.
Santa Rosa Coop site set a new monthly max temperature record of 112 deg., breaking the previous record of 110 deg recorded in 2020, 2017, and 1971. Napa Coop site set a new daily max temperature record of 109 deg., breaking the previous record of 102 deg. set in 2020. Kentfield Coop site set a new daily record of 107 deg., breaking the previous record of 103 deg., set in 1950.
Gilroy Coop site equaled its monthly record max temperature of 112 deg., set in 2017. It also set a new daily record, breaking the previous record of 106 deg., set in 2020. SJC Airport set a new daily max temperature record of 104 deg., breaking the previous record of 99 deg. set in 2008.
SFO ASOS set a new daily max temperature record of 97 deg., breaking the previous record of 93 deg., set in 2004. Downtown Oakland Coop site set a new daily max temperature record of 100 deg., breaking the previous record of 95 deg. set in 2008. Redwood City Coop site set a new daily max temperature record of 107 deg., breaking the previous record of 97 deg., set in 1983.
Salinas Airport set a new daily max temperature of 103 deg., breaking the previous record of 92 deg., set in 2004.
King City Coop site set a new daily max temperature record of 106 deg., breaking the previous record of 105 deg., set in 2020.
San Jose Airport set an all-time record high temperature of 109 deg, beating the previous record 108 deg set in 2017. Gilroy coop site set a monthly high temperature record of 113 deg, beating the previous record 112 deg set the previous day.
King City reported an all-time record high temperature of 116 deg, beating the previous record 115 deg set in 2017.
Redwood City tied its all-time record high temperature of 110 deg set in 1972. It also beat its monthly record 108 deg set in 2020.
Santa Rosa set an all-time record high temperature of 115 deg, beating its previous record 113 deg set in 1913. Downtown Napa set an all-time record high temperature of 114 deg, beating its previous record 113 deg set in 1961.
Livermore tied its all-time record high temperature of 116 deg, which was set the previous day.
Half Moon Bay set a daily record high temperature of 81 deg, beating its previous record 80 deg set in 2004.
Gilroy set a daily record high temperature of 110 deg, beating its previous record 108 deg set in 1957. San Jose set a daily record high temperature of 104 deg, beating its previous record 100 deg set in 1904.
Livermore set a daily record high temperature of 113 deg, beating its previous record 110 deg set in 1944.
As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.
| Event | Date | Age | Sex | Where | Kind |
|---|---|---|---|---|---|
| Heat, Santa Clara Valley Including San Jose | 2022-09-06 | 78 | Male | Unknown | Direct |
| Heat, Santa Clara Valley Including San Jose | 2022-09-06 | 68 | Female | Unknown | Direct |
| Heat, Santa Clara Valley Including San Jose | 2022-09-06 | 39 | Male | Unknown | Direct |
| Heat, Santa Clara Valley Including San Jose | 2022-09-06 | 60 | Male | Unknown | Direct |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2022Every state in 2022This day in weather historyWarnings in California, September 2022
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: 1057713, 1057714, 1057715, 1057711, 1057708, 1057712, 1055364, 1055368, 1055372, 1055379, 1055384, 1055385, 1055386, 1055387, 1055390, 1055392, 1055393, 1057717, 1057718, 1057719, 1057721, 1057722, 1057723, 1057724, 1057725.