047
FXUS66 KSGX 200642
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
1142 PM PDT Thu Mar 19 2026

.SYNOPSIS...
Widespread moderate with areas of major HeatRisk will continue
through Friday. HeatRisk will decrease for the weekend, with minor
cooling. Even with the cooling, temperatures will remain above
average into next week. Patchy marine layer low clouds and fog will
be present at times, most likely to impact the coastal waters and
immediate coast.

&&

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

...NEW AVIATION AND MARINE DISCUSSION BELOW...

Evening update...
Numerous daily and monthly high temperature records were broken or
tied again today, including Idyllwild which broke their monthly
high temperature for the third day in a row with a high of 90
degrees. Indio and Thermal tied the national high temperature
record for March with a high of 108 degrees.

Patchy low clouds and fog have developed just off the coast of far
southern San Diego County again this evening but have yet to make
it over land, though satellite imagery is showing it nearing
Point Loma. Occasional dense fog is possible at the beaches from
about Solana Beach southward tonight into early Friday morning.
The large upper level high currently centered over the lower
Colorado River Valley will shift eastward and weaken slightly on
Friday, allowing for very minor (1 to 2 degrees) cooling west of
the mountains with little change in the deserts.

Previous discussion...
Through Friday widespread temperatures in the 90s to low 100s
expected for the inland valleys, with highs in the mid- 80s to low
90s for coastal areas away from the immediate coast and the lower
elevations of the mountains. In the low deserts, highs will
likely exceed 105 degrees in most locations through Saturday.
Chances for exceeding 110 degrees on Friday are 60 percent for
Indio, 20 percent for Palm Springs, and 10 percent for Borrego
Springs. In the High Desert, temperatures will be in the mid-90s.

Weakening high pressure aloft and strengthening onshore flow will
bring 4 to 8 degrees of cooling Saturday. That will be most
noticeable for locations west of the mountains, but even the deserts
will cool 3 to 5 degrees. A weak low pressure system aloft will move
east through Southern California into the Great Basin sometime
Sunday or Monday. that will bring an uptick in westerly winds
Saturday, which have the potential to turn weakly offshore by Sunday
afternoon into Monday morning. Ridging aloft looks to rebuild Monday
and strengthen into the middle of the week. This ridge isn`t expected
to be as strong as the one over Southern California this week, but
it will be enough to maintain above average temperatures through
next Thursday. Widespread minor with areas of moderate HeatRisk will
be present in the valleys and low desert for much of next week.

With the ridge axis shifted further east today, weak onshore flow
has returned to coastal areas. The weak onshore flow was enough to
allow patchy dense fog along the immediate coast this morning. Areas
of patchy dense fog over the water and at the coast is possible each
morning through Saturday. With the aforementioned passing weak low
pressure onshore flow will briefly increase, making chances of dense
fog less likely for Sunday morning. Low cloud and fog coverage on
Sunday morning may reach into the western valleys. Weak offshore
flow early next week may keep low clouds and fog patchy and more
confined to the immediate coast again.


&&

.AVIATION...
200630Z...SKC across the area currently except for two small patches
of FG just offshore. Chances of patchy FG invading coastal areas
slowly increase overnight. 50% for VIS below 1/2SM after 09Z at KSAN
and 30% for KCRQ. Greater uncertainty for KSNA with a slight (20%)
chance for VIS/cig reductions. Clearing 15Z-17Z. Similar story for
Friday evening and overnight with patchy FG expected to
intermittently reduce vis for coastal areas starting 03-06Z.
Everywhere else, VFR conditions expected through the TAF period.

&&

.MARINE...Chances for fog tonight over coastal waters have lowered
some (30-40 percent for most areas). However, patchy fog is still
expected near the coastline. Vis locally below 1 nautical mile where
fog develops. Vis improvements expected by late morning Friday.
There is greater confidence for areas of fog Friday evening and
overnight with highest chances hear the coastline once again.
Otherwise, no hazardous marine conditions are expected through
Tuesday.

&&

.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-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.

     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