FXUS66 KSGX 210547

AFDSGX



Area Forecast Discussion

National Weather Service San Diego CA

1047 PM PDT Fri Mar 20 2026



.SYNOPSIS... 

Gradual cooling through the weekend with a return of marine layer

low clouds and fog at the coast. Even with the cooling, 

temperatures will remain 15-25 degrees above normal into next 

week, highest on Wednesday during the next peak in the heat.



&&



.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...

SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO

COUNTIES...



...AVIATION/MARINE SECTIONS UPDATED...



At the risk of sounding like a broken record, numerous monthly and

daily record highs were broken again today. In fact, of our

climate sites that reported to day, all but two (Newport Beach and

San Diego) broke or tied their daily record. Nine sites broke or

tied monthly records that were set earlier this week. See the

Record Event Report headlined on our homepage at

weather.gov/sandiego for more details. While the days of monthly

record high temperatures is behind us, several daily high 

temperature records are forecast to be broken or tied every day 

for the next week.



Patchy low clouds are along the coast of Baja California around 15

mi south of the border, but aren't making much northward progress.

Some low clouds and fog may develop along our coasts tonight into

Saturday morning, but confidence is low in where fog will develop

and how long it will last.



The upper level high currently centered over western AZ will

continue to shift east and weaken this weekend in response to a

series of short wave troughs moving into the Western US. This will

allow for some cooling and stronger onshore flow this weekend. For

the mountains westward, HeatRisk will fall to minor to locally

moderate, and the Heat Advisory was allowed to expire for the 

coastal areas, valleys, and mountains. The Extreme Heat Warning 

for the low deserts remains in effect through 8 PM Saturday as

temperatures there remain well over 100 degrees. The weak

troughing and stronger onshore flow will also help the marine

layer rebuild, with more widespread low clouds and fog along the

coast Saturday night into Sunday morning. The marine layer deepens

slightly the following night, with the potential for dense fog on

the coastal mesas by Monday morning. 



The upper level ridge begins to rebuild over So Cal on Monday for

minor warming. The warming trend continues into Wednesday as the

ridge strengthens and moves eastward. By Wednesday highs will 

rise to around 15-25 degrees above normal. The ridge begins to 

weaken and progress eastward through the latter half of the week, 

though the degree to which both of these occur is still uncertain.

Around 29% of the global ensemble members keep the ridge further 

west, maintaining warmer weather even into the end of the week, 

while the remaining members have the ridge axis closer to the 

Plains and weak troughing beginning to develop of the West Coast 

for better cooling. Still no precipitation chances in sight 

through the end of next week. 





&&



.AVIATION... 

210545Z...Mostly clear skies and VFR conditions expected through 

08Z. Areas of FG expected to develop near the coastline 08-11Z for 

San Diego County and 10-13Z for Orange County. Any FG that develops 

will stay mostly within 5 miles of the coastline. 60% chance for vis 

below 1SM at KSAN, 40% at KCRQ, and 30% at KSNA. Scattering out of 

land areas 15-17Z, but may linger at the beaches through 20Z. Low 

clouds return to coastal areas late Saturday evening with slightly 

higher bases. Minor vis reductions (2-5SM) for coastal areas with FG 

along elevated coastal terrain.



&&



.MARINE...Areas of fog with visibility under 1 nautical mile is 

expected to develop over the coastal waters starting 08-10Z, highest 

chances near the coastline (50-60%). Coverage becomes more patchy by 

late Saturday morning with any remaining clouds lifting enough to 

improve visibility. Otherwise, no hazardous marine conditions 

expected through Wednesday night.



&&



.SKYWARN... 

Skywarn activation is not requested. However weather spotters are

encouraged to report significant weather conditions.





&&



.SGX WATCHES/WARNINGS/ADVISORIES...

CA...Extreme Heat Warning until 8 PM PDT Saturday for Coachella 

     Valley-San Diego County Deserts-San Gorgonio Pass near 

     Banning.



PZ...None.



&&



$$



PUBLIC...SS

AVIATION/MARINE...KW