6800ft. 
857
FXUS66 KSGX 061212
AFDSGX
Area Forecast Discussion
National Weather Service San Diego CA
515 AM PDT Thu Aug 6 2026
.SYNOPSIS...
The HeatRisk will continue to slowly increase through Saturday
with widespread major HeatRisk for the deserts and widespread
moderate HeatRisk for Inland Empire and for the mountains below
6500 feet. There will be a slight chance of afternoon showers and
thunderstorms for the mountains through next Tuesday with the
relatively greater chances for this afternoon and again for Sunday
through Tuesday. Gradual cooling and drying will then follow for
the rest of next week.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
.SHORT TERM (Today through Saturday)...
Ensemble output shows precipitable water values peaking this
afternoon, then declining into Saturday afternoon. The peak hourly REFS
90th percentile rainfall is around 0.75 inch for this afternoon
and around 0.25 inch for Friday afternoon. There is a slight
chance of showers and thunderstorms for the mountains for this
afternoon with slowly decreasing chances for Friday afternoon and
Saturday afternoon.
The HeatRisk will continue to slowly increase through Saturday
with widespread major HeatRisk for the deserts and widespread
moderate HeatRisk for Inland Empire and for the mountains below
6500 feet. High temperatures on Saturday will be a few degrees
above average near the coast to 5 to 10 degrees above average for
the deserts. High temperatures on Saturday will range from the mid
70s to lower 80s near the coast to the mid 90s to 105 for the
Inland Empire with 110 to 114 for the lower deserts.
Night and morning will continue to spread into coastal areas, but
with some occasional disruptions in coverage from mid level
monsoonal moisture and clouds.
&&
.LONG TERM (Sunday through Wednesday)...
The Extreme Heat Warning for the deserts and Heat Advisory for the
mountains and Inland Empire has been extended through Sunday with
only a slight decline in HeatRisk on Sunday. Greater declines are
expected for Monday and Tuesday with moderate HeatRisk for next
Tuesday confined mostly to the deserts.
Ensemble output shows another peak in precipitable water values
for Sunday afternoon, similar to the peak for this afternoon, then
a gradual slow decline through next week. A slight chance for
afternoon showers and thunderstorms for the mountains will
continue for Sunday through Tuesday with gradual cooling and
drying for the rest of next week. For Thursday of next week, high
temperatures for the deserts and near the coast will be around
average and could be as much as 4 to 8 degrees below average for
the inland valleys. For Thursday of next week, high temperatures
could range from the 70s near the coast to the mid 80s to mid 90s
for the Inland Empire with 106 to 110 for the lower deserts.
&&
.AVIATION...
061100Z....Coasts/Valleys...Areas of low clouds based 1200-1700 ft
MSL continue to linger over coastal areas and western valleys early
this morning. Coverage will remain partial through this morning with
clouds intermittently impacting coastal TAF sites. Clouds scatter to
the coastline by 16z Thu. VFR conditions expected Thursday afternoon
and evening with very low chances for any cigs before 06z Fri.
Thereafter, clouds will slowly develop over coastal areas with
slightly lower bases and patchier coverage than this morning.
.Mountains/Deserts...ISO SHRA/TSRA (15% chance) may develop along
mtn ridges 20-23z Thu. Otherwise, SCT-BKN clouds AOA 20,000ft MSL
with unrestricted VIS through Thursday evening.
&&
.MARINE...
No hazardous marine conditions are expected through Monday.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 8 PM PDT Sunday for Riverside County
Mountains-San Bernardino County Mountains-San Bernardino
and Riverside County Valleys-The Inland Empire-San Diego
County Mountains.
Extreme Heat Warning until 8 PM PDT Sunday for Apple and Lucerne
Valleys-Coachella Valley-San Diego County Deserts-San
Gorgonio Pass near Banning.
PZ...None.
&&
$$
PUBLIC...17
AVIATION/MARINE...KW
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