FXUS66 KSGX 230900
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
200 AM PDT Sun Aug 23 2026

.SYNOPSIS...
Monsoonal moisture will decrease this weekend, with a slight 
chance of showers and thunderstorms for the mountains and lower
deserts returning for Monday afternoon. Above average high and 
low temperatures will continue through next week. Widespread 
moderate to locally major HeatRisk for the coast, valleys, and 
mountains except near the beaches and for the higher elevations in
the mountains, with major to extreme HeatRisk for the lower 
deserts.

&&

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

Today through tomorrow night...

A strong ridge remains in place through this weekend, with 
temperatures remaining around 5 to 10 degrees above the seasonal 
average for this time of year. There will be some monsoonal moisture 
passing through the mid levels over the region by later on which may 
allow for a rogue shower or two to develop over the mountains, 
although it will likely struggle to develop into a thunderstorm, 
given the lack of instability and overall flow. The marine layer as 
of this morning has struggled to form with only patchy ceilings 
along some of the coastal sites, and this will be the case again for 
tonight. Be advised of all heat products issued, and be sure to stay 
hydrated!

Monday through Friday...

There will be a slightly better influx of monsoonal moisture for 
Monday through the rest of the week, although the mid-level flow 
will still not be favorable for afternoon shower and thunderstorm 
development to be significant. However, there will still be the 
chance of isolated showers and thunderstorms each afternoon over the 
mountains and adjacent deserts, especially by later in the week. It 
will also remain very hot, with only a slight cooldown on Monday and 
then gradually increasing towards the middle of the week as the 
ridge remains stationary and locked in over the desert southwest, 
translating to the persistence of high temperatures remaining on an 
average of 5 to 10 degrees above average throughout the rest of the 
work week. The marine layer will likely have similar results, with 
struggles to form overnight and likely impacting only the coastal 
areas for the most part.

&&

.AVIATION... 
230530Z...Coast...Mostly clear skies over the majority of the coast 
with just a few clouds based around 1,000ft MSL over south SD 
coastal waters. Clouds will become more widespread towards 9-10Z but 
remain patchy and intermittent majority of the night. Moderate 
confidence on cigs impacting coastal SD between 10-15Z with bases 
500-1,000ft MSL. Lowered vis 2-4 SM expected for higher coastal 
terrain, locally >= 1 SM. Clouds clear over land by 16Z. 

Otherwise...VFR conditions through the TAF period with mostly clear 
skies through 18Z. Mid/high clouds AOA 20,000ft MSL expected east of 
the mountains in the afternoon Sunday.

&&

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

&&

.BEACHES...
A 4-5 foot southerly swell at 13-15 seconds will move into the area 
Wednesday and Thursday, leading to elevated surf for the south 
facing beaches of northern San Diego County and Orange County. 
Breaking waves of 4 to 6 feet are likely, with the potential for 
localized sets to 8 feet. Surf gradually subsides on Friday.

&&

.SKYWARN... 
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Extreme Heat Watch from Tuesday morning through Friday evening 
     for Apple and Lucerne Valleys-Orange County Coastal Areas-
     Orange County Inland Areas-Riverside County Mountains-San 
     Bernardino County Mountains-San Bernardino and Riverside 
     County Valleys-The Inland Empire-San Diego County Coastal 
     Areas-San Diego County Mountains-San Diego County Valleys-
     Santa Ana Mountains and Foothills.

     Heat Advisory until 10 AM PDT Tuesday for Orange County Inland 
     Areas-Riverside County Mountains-San Bernardino County 
     Mountains-San Bernardino and Riverside County Valleys-The 
     Inland Empire-San Diego County Mountains-San Diego County 
     Valleys-Santa Ana Mountains and Foothills.

     Extreme Heat Warning until 8 PM PDT Friday for Coachella Valley-
     San Diego County Deserts-San Gorgonio Pass near Banning.

PZ...None.

&&

$$

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