811
FXUS66 KSGX 260948
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
248 AM PDT Sun Oct 26 2025

.SYNOPSIS...
Cool conditions with breezy west winds in the mountains and
deserts will continue today. Daytime temperatures will be about 5
degrees below normal in the coastal areas and valleys, and a
little above normal in the deserts. The marine layer remains deep
enough to allow clouds to reach the inland valleys and foothills
this morning. High pressure and periods of offshore flow will bring
warmer and drier weather with a shallower marine layer into next
weekend.

&&

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

This morning...The marine layer is a little deeper than yesterday
morning with low clouds extending into portions of the Inland
Empire and the foothills of San Diego County. The strength of the
inversion above the marine layer remains about as strong as
yesterday so clearing of the low clouds will likely be similar to
yesterday. The low pressure trough moving inland to the north is
also bringing variable mid and high clouds to Socal along with
stronger onshore flow. So far, the wind-favored locations have
reported wind gusts of 25-35 mph. The onshore flow is expected to
peak this afternoon with wind gusts of 30-40 mph in the wind-prone
locations. High temperatures today will be several degrees below
seasonal averages west of the mtns and near or a few degrees above
seasonal averages in the deserts.

The flow aloft above SoCal becomes high-zonal for Monday as the
low/trough moves inland to the north. This will maintain the
onshore flow and keep a marine layer presence in the coastal areas
where high temperatures will be near or a little below seasonal
averages. Inland areas will warm somewhat with temperatures near
or as much as 7 degrees above average.

Building high pressure aloft and offshore flow will bring
significant warming and a reduction in the marine layer presence
for Tue through Thu. Wednesday will likely be the warmest day,
with daytime temperatures ranging from about 5 degrees above
average in the coastal areas and deserts to as much as 15 degrees
above average in the inland valleys. Short-range, high-resolution
models now indicate that the offshore flow will peak Tue
afternoon-Wed morning producing northeast to east winds locally
gusting 45-55 mph in and below the Cajon Pass, the San Gorgonio
Pass and in the Santa Ana Mountains. Easterly winds gusting 35-45
mph in the mtns and coastal foothills of San Diego County are also
likely. The offshore flow will also bring significantly lower
humidity to the inland areas, especially Tue afternoon when
relative humidities could reach as low as 12% in the inland
valleys.

Temperatures lower a little towards the end of the week as the
high pressure ridge weakens in response to a weak shortwave trough
moving inland to the north. The marine layer returns to the
coastal areas as weak onshore flow develops. At this time,
forecast details are still a little uncertain due to the spread in
model solutions.

&&

.AVIATION...
260930Z...Coast/Valleys...Low clouds based 1000-1500 ft MSL have
spread into San Diego and Orange Counties up to 20 miles inland.
Clouds spreading into portions of the Inland Empire including KONT
(30% KSBD) over the next few hours. Vis reductions (1-5SM) mainly
limited to elevated coastal terrain/valleys and the Inland Empire.
Similar clearing pattern expected on Sunday from what was seen on
Saturday; clearing to the coast by 18-20Z Sun. Low clouds return to
coastal SD County 00-03Z Mon, then spread north into Orange County
overnight. Similar to slightly lower bases and 10-15 miles inland
extent.

Mountains/Deserts...VFR conditions expected through the TAF period.
FEW-SCT high clouds AOA 20,000ft MSL through Monday morning. Wind
gusts 25-35 kts along and east of east-facing mtn slopes Sunday
afternoon and evening.

&&

.MARINE...
Northwest winds gusting to 18kts possible this afternoon and evening
in the outer coastal waters near San Clemente Island. Otherwise, no
hazardous marine conditions are expected through Thursday.

&&

.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...PG
AVIATION/MARINE...KW

NWS Tucson (SGX) Office