549
FXUS66 KSGX 252006
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
106 PM PDT Tue Aug 25 2026

.SYNOPSIS...
A slight chance of afternoon showers and thunderstorms will
continue for the mountains through Wednesday as monsoonal moisture
slowly decreases. High and low temperatures will continue to rise
through Thursday, to as much as 10 to 15 degrees above average,
with not much change for Friday. The highest HeatRisk is expected
for Thursday and Friday with widespread Extreme HeatRisk for the
inland valleys and inland Orange County. This will be followed by
a cooling trend for the weekend into early next week with stronger
onshore flow and drier southwest flow aloft, with high
temperatures falling to around average for next Monday.

&&

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

This afternoon...Skies are clear except over the mountains where
cumulus clouds have developed. There is a chance that some showers
or tstms could develop over the mtns later this afternoon and may
drift into the deserts. Temperatures are generally higher than at
this time yesterday...especially in the lower deserts where
temperatures are as much as 12 degrees higher.

Extensive ridge of high pressure will continue the warming trend through
Thursday, with warmer days and warmer nights. High temperatures
on Thursday will range from the 80s near the coast to 106 to 112
for the Inland Empire with 110 to 116 for the lower deserts. Low
temperatures on Thursday will be mostly in the 70s for the coast
and valleys and in the mid 80s to mid 90s for the lower deserts.

The highest HeatRisk for the coast and valleys is expected on
Thursday and Friday with widespread Extreme HeatRisk for the
inland valleys and inland Orange County with Major HeatRisk for
most other areas with Moderate HeatRisk limited to the beaches.

Mid level monsoonal moisture will remain in place today with a
slight decrease on Wednesday and a greater decrease on Thursday. A
slight chance of afternoon showers and thunderstorms, mostly for
the mountains, will continue through Wednesday.

For Saturday through Tuesday, high pressure will begin to weaken
across the area as a low pressure system develops near the
California coast, strengthening onshore flow at the surface. High
temperatures will fall to around 5 degrees above average on
Sunday and a few degrees below average for the mountains and
inland valleys on Monday. Monday high temperatures will range from
the mid 70s to lower 80s near the coast to the 90s for the Inland
Empire with 104 to 108 for the lower deserts.

&&

.AVIATION...
251800Z...Coast...VFR through early Wednesday morning. Patchy low
clouds based 600-900 ft MSL redevelop over coastal areas starting 08-
10z Wed. Best chance for cigs will be in San Diego County from 12-
15z. Minor vis reductions of 2-6SM down to sea level and patchy
dense FG along elevated coastal terrain where cigs develop. Any low
clouds scatter out by 16z.

Mountains/Deserts...Cumulus based around 9000 feet MSL with ISO TSRA
and CB tops to 40000 feet over mountains 20-01Z. Any TS that
develops could produce gusty, erratic winds. VFR conditions prevail
otherwise.

Regionwide...FEW-SCT clouds AOA 15000 feet MSL through the period.

&&

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

&&

.BEACHES...
A 4-5 foot southerly swell (from 170 degrees) at 12-14 seconds will
move into the area Wednesday morning, leading to elevated surf for
the south facing beaches of northern San Diego County and Orange
County through Thursday. Surf of 3 to 6 feet, with sets up to 7 feet
are expected.

&&

.FIRE WEATHER...
For at least the next three days...low humidity and locally gusty
westerly winds could produce elevated fire weather conditions
during the afternoon hours in areas above 2,000 ft, especially in
and below mountain passes and canyons. A slight chance of afternoon
showers and thunderstorms will continue for the mountains through
Wednesday as monsoonal moisture slowly decreases. High and low
temperatures will continue to rise through Thursday, to as much as
10 to 15 degrees above average, with not much change for Friday.
This will be followed by a cooling trend for the weekend into
early next week, with stronger onshore flow and drier southwest
flow aloft with high temperatures falling to around average for
next 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 Friday for Orange County Coastal
     Areas-Riverside County Mountains-San Bernardino County
     Mountains-San Diego County Coastal Areas.

     Extreme Heat Warning until 8 PM PDT Friday for Apple and Lucerne
     Valleys-Coachella Valley-Orange County Inland Areas-San
     Bernardino and Riverside County Valleys-The Inland Empire-
     San Diego County Deserts-San Diego County Mountains-San
     Diego County Valleys-San Gorgonio Pass near Banning-Santa
     Ana Mountains and Foothills.

PZ...None.

&&

$$

PUBLIC/FIRE WEATHER...PG
AVIATION/MARINE...KW

NWS San Diego (SGX) Office