030
FXUS66 KSGX 180933
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
233 AM PDT Sat Oct 18 2025

.SYNOPSIS...
Weak offshore flow will continue Saturday and Sunday. Near to
slightly above average temperatures expected through Monday, before
below average conditions return for the middle of the week. Gradual
warming for the end of the week, with cooler conditions possible for
next weekend. Marine layer low clouds and fog will be mostly absent
from the coast this weekend, likely returning Monday and becoming
more widespread into the middle of the week.

&&

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

Weak high pressure aloft will set in this weekend, bringing dry
conditions and near to slightly above average temperatures. Weak
offshore flow will continue each morning this weekend, which will
help inhibit low cloud development. Offshore winds will be
slightly elevated on the coastal slopes of the mountains, locally
into the foothills, with peak of the winds in the early morning
hours. Northeast to east wind gusts will be 30 mph or less this
morning. Wind sheltered valley locations will again experience
overnight low temperatures that fall into the 40s to low 50s.
Offshore winds will weaken Sunday, with slightly warmer overnight
low temperatures.

A closed low will linger west of Southern California this weekend,
before slowly moving east Monday and Tuesday. By Wednesday, the low
is expected to quickly move east across Southern California. This
will bring an increase in cloud coverage and cooler conditions.
Westerly winds may become elevated over the mountains, locally into
the deserts. By Wednesday, highs for inland locations are expected
to be 7 to 12 degrees below average, with some mountain locations
seeing highs near 15 degrees below average. Rain chances associated
with this system continue to look marginal. Global ensembles have
shown a drying trend over the last few runs, with chances of
measurable rainfall occurring currently less than 10 percent. The
best chances for any accumulating rain are on the coastal mountain
slopes. Areas of patchy drizzle cannot be ruled out west of the
mountains on Wednesday, especially with the increase in onshore flow
and rapid deepening of the marine layer.

As the low continues to move east weak ridging will set up again
over Southern California for Thursday and Friday. This will bring a
few degrees of warming, weak offshore flow, and a shallower marine
layer. For next weekend, we`re monitoring the potential for a deep
trough of low pressure from the Gulf of Alaska to dig south into the
US West Coast. Currently, most of the ensemble guidance keeps the
low off the coast of the Pacific Northwest through next Saturday
(Oct 25), which would keep us dry through then. About 20 percent of
solutions trend towards a wetter outcome for Southern California on
Saturday with the low slightly further south and east. Current
forecast for next Saturday keeps chances of precipitation under 15
percent, temperatures below average, and has an increase in cloud
coverage.

&&

.AVIATION...
180830Z....Clear and VFR conditions through early Sunday.

&&

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

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.

&&

$$

PUBLIC...CO
AVIATION/MARINE...Munyan

NWS Tucson (SGX) Office