712
FXUS66 KSGX 171040
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
240 AM PST Sat Jan 17 2026

.SYNOPSIS...
Patchy dense fog along the immediate coast early this morning will
be pushed offshore later. Santa Ana winds are developing near the
passes and foothills of the mountains and will continue into
Sunday, with peak gusts around 45 mph. Winds weaken Sunday
afternoon. High temperatures as much as 10 to 15 degrees above
average for the valleys will continue through Sunday followed be a
gradual cooling trend through the end of next week.

&&

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

Lots of high clouds above a very shallow marine layer. Some low
clouds and patchy, dense fog made it to the coast last evening but
are now being pushed offshore as the diurnal drainage winds and
developing offshore flow combine. Sfc pressure gradients remain
offshore with -8.8 mb SAN-TPH and -3.3 mb SAN-DAG. In the last
hour, a handful of locations in the wind-prone locations reported
wind northeast winds gusting to 40+ mph with one location
reporting a gust of 54 mph. Low temps this morning are likely to
be warmer than yesterday due to the high cloud cover.

Today and Sunday...
The offshore winds are peaking this morning but will then
gradually weaken for this afternoon into Sunday morning as
offshore pressure gradients weaken. The weakening offshore winds
will allow a sea breeze to develop Sunday afternoon. High pressure
aloft and the offshore winds will combine to produce daytime high
temperatures 10-15 degrees above normal from the coast to the
foothills. Elsewhere, high temperatures will be 5 to 10 degrees
above normal. The National Blend Model indicate a 75-100%
probability of 80+ degrees for the valleys and inland coastal
areas today. Chances lower to 35-90% on Sunday as the weak sea
breeze spreads marine layer air inland.

Weaker offshore flow will return for Monday and Tuesday mornings,
with northeast to east winds gusting 35-40 mph in the passes and
foothills. High-resolution models still show a weak, short-lived
coastal eddy each of those mornings. Some of those high-res models
also indicate that marine layer clouds and fog are likely to
return to the immediate coast Monday and Tuesday mornings. The
marine layer presence would also moderate temperatures in the
coastal areas faster. The upper level ridge does begin to weaken
during this period for gradual cooling even of the inland areas.
More persistent onshore flow returns for Wednesday and Thursday
for a noticeable cooling trend and highs returning to within a few
degrees of normal by Thursday.

Beyond Thursday, a closed low about 650 miles southwest of San
Diego will be drawn into the mean westerly flow aloft by a
shortwave trough moving southeast from the Pac NW and eventually
moving across the region sometime Fri-Sat. A significant number of
the Global Ensemble members indicate the potential for
precipitation for next Fri-Sat but it`s not yet a majority of
ensemble members. As a result, much uncertainty remains as to the
timing and amounts of any precipitation.

&&

.AVIATION...
171000Z...FEW high clouds and VFR conditions prevail throughout most
of the region through the period. Patches of low clouds and FG based
around 200 ft MSL at immediate coast will intermittently reduce vis
down to 1/4SM through 15z this morning.

Additionally, offshore winds will be elevated along coastal slopes
and into adjacent foothills through 06Z Sun with gusts intermittently
25-35 kts. Gusts locally to 40 kts through and just below the Cajon
Pass. Gusts intermittently 15-25 kts through portions of the Inland
Empire. Winds decrease Saturday night with gusts locally to 25 kts
along coastal slopes.

&&

.MARINE...
Areas of dense fog this morning over the waters, locally reducing
visibility to less than 1 nautical mile. Fog is expected to lift
late this morning. Otherwise, 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...PG
AVIATION/MARINE...KW

NWS San Diego (SGX) Office