190
FXUS66 KSGX 150422
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
922 PM PDT Sat Mar 14 2026

.SYNOPSIS...
After a cooler day today, a great warming trend is expected for the
upcoming week, unfolding into a long duration heat wave. As high
pressure moves over the area, highs will be 20 to 30 degrees above
normal with moderate to high heat risk for all areas. The heat
will peak later next week, with a gradual cooling trend thereafter.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

...AVIATION AND MARINE SECTIONS UPDATED...

Update: At this hour, low clouds are continuing to form along the
coastal areas of San Diego County. These will intermittently stretch
into some of the coastal basins and inland areas within 10 miles
from the coast throughout the night. The ridge is going to further
strengthen into next week and bring about unprecedented heat for
this time of year. This will also help to weaken onshore flow and
keep the marine layer quite depleted beginning tomorrow night.
Temperatures will gradually continue to get hotter. Probabilities of
temperatures exceeding 100F within the IE will jump up to 90% for a
few of the lower-lying areas, as well as the possibility of a few
temperatures exceeding 110F within the Coachella Valley. Other
inland areas will likely be over 90F, with even slightly hotter
temperatures on Friday. There will likely be most locations breaking
daily records, with many breaking monthly records, and possibly a
few flirting with all-time records. The duration of this extreme
heat event is what makes it so significant. There will also likely
need to be heat advisories (possible heat warnings) for the
mountains and lower deserts by later in the week during the peak
heating as a very strong ridge (nearly exceptional for this time of
year) remains parked over the region, with heights aloft at the 500
mb level approaching 600 dm. There will finally be some relief to
this intense heat beginning the following weekend as the ridge
finally begins to break down. Throughout this long duration of very
hot temperatures, it is important to say hydrated and check up on
loved ones vulnerable to heat (or without AC). Stay tuned for the
latest updates to our Heat products at weather.gov/sgx/

Previous discussion submitted at 109 PM:

A weak trough to the north and weaker area of high pressure to the
south has the led the marine layer to deepen. A coastal eddy over
the California Bight has contributed to low clouds and fog near the
coast this morning. Low clouds will dissipate some this afternoon
over the water, then reform and move back further inland overnight.

An area of high pressure will begin to build off the coast by
Sunday, where a long duration heat wave is expected to last through
much of next week. Sunday temperatures will warm another 5 to 10
degrees across inland valleys west of the mountains with highs
reaching into the 90s across the Inland Empire and lower deserts.
The ridge will amplify further into Monday and Tuesday, centering
over the region. Hot temperatures in the valleys will expand
closer to the coast and foothills with plentiful 90s for western
valleys and closer to 100 degrees across the lower deserts on
Monday.

All regions will continue to warm another 2-5 degrees on Tuesday. By
Tuesday, chances for 100 degrees are around 20-40% for the southern
Inland Empire and northern Orange County, closer to 50-80% across
the northern Inland Empire. Models show similar temperatures
expected on Wednesday as 850mb temps climb to near 25C. The only
places that may warm a few degrees would be across the mountains
with areas near Big Bear Lake closing in on 80 degrees (their record
high for March) and Julian and Idyllwild getting into the mid to
upper 80s. Seeing that these places in the mountains will be this
warm and even warmer by late week, please avoid any outdoor
recreation in these areas each afternoon this week if at all
possible.

The area of high pressure will peak in strength by Thursday and
Friday over SE California into Arizona, billowing into a staggering
595 dm, very strong for this time of year. The hottest temperatures
of the heat wave still look to occur during this time. Chances to
see 100 degree temperatures will be around a 50-50 chance from El
Cajon to Escondido to Anaheim with a general 30-60% chance across
inland valleys east of the 5 and the 15 in Orange and San Diego
Counties. The IE will see temperatures over 100 with about a 30-50%
chance to see highs reach 105 degrees, especially near the city of
San Bernardino. Mountain areas will continue to be hot with highs in
the upper 80s to near 90 from Idyllwild to Julian to Lake Arrowhead.
The immediate coast will be a tougher forecast in this pattern as
weak / cool onshore winds off the cold ocean have a large influence
on the exact temperatures. Some lucky beaches along San Diego County
may stay in the 70s for much of the upcoming week making for some
beautiful beach weather.

As the high slowly weakens and pushes into Arizona late week, hot
temperatures will be last to cool across the Coachella Valley and
Anza-Borrego desert. High heat risk will begin in this area on
Thursday, lasting through Saturday, so please make sure to find air
conditioned spaces and limit time outdoors. Not only will this area
shatter record temperatures for the month of March, some may even
break records for April! Since 1894, the hottest April temperature
in Indio is 110 degrees. NBM gives this about a 75% chance of
going over this value! Chances to break the April records at Palm
Springs (112 degrees) is around 25% and around 80% at Thermal (110
degrees). Quite incredible for this time of year! Models are in
fair agreement of a trough beginning to loom offshore by next
weekend, bringing a gradual cooling trend first along and west of
the mountains by next Saturday, then across all areas thereafter.

&&

.AVIATION...
150500Z...Patchy low clouds based 800-1200 ft MSL will move inland
to about 15 miles overnight, with vis 2-5 SM over coastal highlands.
Both cigs and vis likely lower slightly towards 09Z, with MVFR vis
possible at coastal sites. Low clouds clear to coast 15-17Z.
Patchier low clouds 400-800 ft MSL develop and move inland after 06Z
Mon.

Elsewhere, breezy offshore winds develop Sun 18Z-03Z in west
foothills locally into eastern valleys, with gusts to 20-25 kts.

&&

.MARINE...No hazardous marine conditions are expected through
Wednesday.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory from 10 AM Monday to 8 PM PDT Friday for Orange
     County Coastal Areas-Orange County Inland Areas-San
     Bernardino and Riverside County Valleys-The Inland Empire-
     San Diego County Coastal Areas-San Diego County Valleys-
     Santa Ana Mountains and Foothills.

PZ...None.

&&

$$

PUBLIC...Stewey
AVIATION/MARINE...CSP

NWS San Diego (SGX) Office