569
FXUS66 KSGX 270005
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
505 PM PDT Wed Aug 26 2026

.SYNOPSIS...
Persistent high pressure will continue hot days and near-record
warm nights through Friday night, with a slight chance of showers
and thunderstorms for the mountains this afternoon and Friday
afternoon. High pressure will weaken for the weekend into early
next week with high temperatures cooling to around average next
Monday. For Tuesday and Wednesday of next week, there is a 10 to
20 percent chance for an increase in clouds and a chance of
precipitation from a tropical system that has yet to develop.

&&

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


...UPDATED AVIATION DISCUSSION...

This afternoon...Mid and high clouds moving into San Diego County
from the south could produce isolated light showers and possibly
a tstm or two over the next several hours, mainly in the mountains
but a few light showers could develop over the valleys and coastal
areas. Temperatures are mostly a few degrees higher than at this
time yesterday.

Through friday...High pressure will continue to bring hot weather to
Socal. High temperatures will be around 10 degrees above average
with low temperatures as much as 15 to 20 degrees above average
for the lower elevations of the mountains. High temperatures will
range from the 80s near the coast to 100 to 108 for the Inland
Empire with 112 to 116 for the lower deserts. Low temperatures
will be mostly in the 70s for the coast, valleys, and high desert
and in the mid 80s to mid 90s for the lower deserts. Low
temperatures will be around 80 for the lower elevations of the
mountains. The highest HeatRisk is expected on Thursday with
widespread Moderate to Extreme HeatRisk for the valleys, inland
coastal areas, and lower deserts. While the high temperatures will
likely not tie or exceed existing records, many records for
warmest overnight low temperatures could be tied or broken, most
likely on Thursday and Friday.

A cooling trend is expected for Saturday into the middle of next
week as high pressure aloft weakens and shifts to the southeast in
response to a developing trough of low pressure near the
California coast which will strengthen lower-level flow onshore.
High temperatures will cool to around average for next Monday with
low temperatures cooling to slightly above average.

There could be some increase in clouds and a chance of
precipitation around Tuesday or Wednesday of next week from
moisture from a tropical system that has yet to develop.

&&

.AVIATION...
270000Z...Coast...VFR conditions are expected to continue at most
sites through the TAF period with low clouds mainly sticking to the
near shore waters. Highest chances for low clouds to move inland
will be over the southern SD County coast with bases starting around
1,000-1,500ft MSL after 07-08Z. Patchy low clouds with bases 200-
900ft MSL have a 30-40% chance of moving into SD up to 15 miles in
some areas after 12-15Z. Vis reductions of 1SM or less will be
possible where low clouds/FG develop. Low clouds clear the coast by
16z.

Mountains/Deserts...Cumulus based around 9,000ft MSL with ISO TSRA
and CB tops to 40,000ft MSL over mountains into adjacent deserts
continue through 01Z. Conditions calm overnight with lower
chances(less than 10%) for TS forming over the SD mountains Thursday
afternoon. There is a 15-20% chance for ISO TSRA over the Riverside
and San Bernardino county mountains 21Z Thursday -01Z Friday. Any TS
that develops could produce gusty, erratic winds.

Regionwide...High clouds AOA 15,000ft MSL will continue to increase
overnight with BKN Cigs 15,000-20,000ft MSL after 08Z.

&&

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

&&

.BEACHES...
A 4-5 ft southerly swell (from 170 degrees) at 12-13 seconds will
continue to produce elevated surf through Thursday, particularly for
south-facing beaches of northern San Diego County and Orange County.
Surf of 3 to 6 feet, with sets up to 7 feet are expected. Check the
Coastal Hazard Message for details on Beach Hazards.

&&

.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.

     Beach Hazards Statement through Thursday evening for Orange
     County Coastal Areas-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...PG
AVIATION/MARINE/BEACHES...Villafane