Inland areas experienced a heat wave August 25th through the 29th, while parts of the region saw wildfires breakout as well.
Every event with a place to put it; 11 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 SGX wrote it up.
Inland areas experienced a heat wave August 25th through the 29th, while parts of the region saw wildfires breakout as well.
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 Diego, CA wrote its last area forecast discussion before the first event at Aug 24, 8:16 AM PST, 4 hours 22 minutes earlier.
Area Forecast Discussion
National Weather Service San Diego CA
916 AM PDT Tue Aug 24 2021
.SYNOPSIS...
A slow expansion of high pressure will bring warmer temperatures
for the remainder of the work week, along with a shallower marine
layer reducing coastal cloud coverage during the overnight
periods. Abundant smoke aloft will produce hazy skies over the
next couple of days. A slight increase in moisture should bring
milder temperatures and some potential for isolated thunderstorms
to the mountains/deserts as early as Sunday, although uncertainty
remains in the pattern.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING
ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN
BERNARDINO COUNTIES...
MORNING UPDATE...
As predicted by HRRR smoke products, we're seeing considerably
thicker smoke across the region this morning, with hazy skies and
reduced visibility. The majority of the smoke is elevated in
nature, although some potential for mixing to the surface is
indicated through tomorrow, particularly for higher elevations
(namely the mountains and High Desert). For those interested, air
quality information can be viewed at www.airnow.gov, with
forecasts available from sdapcd.org (San Diego County) and
aqmd.gov (Orange/Riverside/San Bernardino counties).
With increasing pressure and a weaker inversion this morning
(~7C), marine layer clouds are much less extensive and are
clearing quickly. Look for warmer temperatures today, up about 5
degrees on average, although highs will still be below normal for
this time of year.
No forecast changes have been made so far this morning. The main
priority today will be to evaluate how best to move forward with
the current Excessive Heat Watch, as Heat Risk looks to be rather
marginal for this event. See below for the previous discussion.
.SHORT TERM (Today through Thursday)...
A weak trough of low pressure will remain near the West Coast with
high pressure to the east continuing the warming trend for inland
areas into Thursday or Friday. High temperatures will warm to
around average today and to 5 to 10 degrees above average for
inland areas on Thursday.
The HRRR continues to show mostly higher level smoke spreading
across the area from the southwest into Wednesday with the smoke
beginning to decrease from the northwest late Wednesday into
Wednesday night. The HRRR also shows some of that smoke may mix
down to lower elevations with greater near surface smoke for the
deserts, mountains, and inland valleys for late tonight into
Wednesday. Otherwise, skies will generally appear hazy from the
smoke aloft, but thicker layers of smoke could occasionally
partially obscure the sky at times.
The marine layer will gradually become shallower with night and
morning low clouds and fog not spreading as far inland. Mid level
moisture from the southwest associated with Tropical Storm Marty
could bring some mid level clouds Wednesday and some afternoon
clouds for the mountains.
The Excessive Heat Watch for the lower deserts continues for
Wednesday through Friday. However heat risk values from the
current forecast temperatures only result in moderate heat risk
for Wednesday and Thursday, insufficient for an Excessive Heat
Warning. Even on Friday, high heat risk values cover only a very
limited area which would be very marginal for an Excessive Heat
Warning.
&&
.LONG TERM (Friday through Tuesday)...
High temperatures on Friday will be similar to Thursday with very
slight day to day differences for most areas for Saturday into
early next week. High temperatures for the lower deserts may not
be quite as hot for Sunday into early next week as lower level
monsoonal moisture slowly increases.
NBM deterministic dewpoints show lower dewpoints for Palm Springs
and Thermal continue into Friday followed by a gradual increase
for Saturday into Tuesday reaching the lower to mid 60s for Palm
Springs on Tuesday and to around 70 for Thermal on Tuesday.
A slight chance of thunderstorms continues in the mountains each
afternoon beginning Sunday, mainly in the mountains. About 25
percent of ensemble members of the ECMWF have measurable rainfall
for Big Bear on Sunday, around half on Monday, and 20 percent on
Tuesday.
&&
.AVIATION...
241615Z...Coast/Valleys...Patchy low clouds mainly in coastal San
Diego County with bases 1500-1800 feet MSL and tops to 2000 ft MSL
will mostly clear by 18Z. Patchy low clouds will occur again mainly
06Z-17Z Wed within 10 miles of the coast with bases 1000-1500 ft MSL
and tops to 1600 ft MSL along with local vis 2-4 miles in BR.
Otherwise, smoke aloft may reduce slantwise visibility through at
least Wed morning, but surface vis will remain mostly
unrestricted.
Mountains/Deserts...FEW-SCT clouds above 10000 feet MSL will occur
through Wed morning. Smoke aloft may reduce slantwise visibility
through at least Wed morning, but surface vis will remain
unrestricted.
&&
.MARINE...
No hazardous marine conditions expected through Saturday.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Watch from Wednesday morning through Friday
evening for Coachella Valley-San Diego County Deserts-San
Gorgonio Pass Near Banning.
PZ...NONE.
&&
SYNOPSIS/MORNING UPDATE...Rodriguez
SHORT TERM/LONG TERM...17
AVIATION/MARINE...MaxwellThe national radar mosaic for the moment the first event began.
8 excessive heat, 3 wildfire. Local standard time, as filed.
The Rock Fire near Anza burned 295 acres and destroyed 4 homes and 8 outbuildings. This fire led to evacuation orders for portions of the city of Anza. Damage amounts are estimated.
The region saw high temperatures between 100 and 105 degrees.
The region saw high temperatures over 115 degrees. The Palm Springs ASOS reported a high of 117 on the 27th.
The region saw high temperatures over 115 degrees. Ocotillo Wells reported a high of 118 degrees on the 26th.
The region saw high temperatures in the upper 80s and lower 90s. Idyllwild reached 91 degrees on the 27th and 29th.
The area saw temperatures soar near 100 degrees each day.
The area reported high temperatures up to 110 degrees.
The region saw widespread 90s with some locales hit near 100 degrees, including Yorba Linda on the 26th.
The region saw widespread 90s with some locales hit near 100 degrees, including the Ramona ASOS on the 27th.
The South Fire burned 819 acres below the Cajon Pass until September 2nd. The led to a series of evacuation warnings and orders along with road closures. 4 homes and 14 other structures were destroyed. Damage amounts are estimated.
The Chaparral Fire burned 1,427 acres and was contained on September 1st. This fire led to road closures, as well as a small area of evacuation warnings and orders. A firefighter was injured along with two structures destroyed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2021Every state in 2021This day in weather historyWarnings in California, 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: 980570, 979673, 979674, 979675, 979676, 979677, 980565, 980566, 980567, 980575, 980576.