179
FXUS66 KSGX 062221
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
221 PM PST Sat Dec 6 2025

.SYNOPSIS...

Increasingly warm, and dry conditions are in store for next week
with periods of weak to locally moderate Santa Ana winds. Patchy
fog possible tonight and Sunday night.

&&

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

Clear skies and weak onshore flow prevails this afternoon. High
temperatures are leveling off a few degrees above and below 70F
inland. Lows tonight will be slightly more mild than this mornings
lows, still seasonably typical. Very patchy fog may develop
overnight tonight over the coastal waters (40-50% chance) and over
coastal areas (15-25% chance, locally higher in Orange County).
There is a similarly low potential for patchy fog for the same areas
Sunday night into Monday morning.

Over the next few days, the broad upper high pressure area currently
a few hundred miles west of San Diego will slowly expand east to
cover California, then amplify northward, cutting off what is left
of the onshore flow and warming temperatures up to 10-20 degrees
above average by Tuesday. Highs likely above 80F just a few miles
inland of the coast. From Tuesday through Friday, confidence is high
that the ridge will keep its general positioning over the Western
US. For each of these four days, around a 30% chance for high
temperatures to exceed 85F in the inland valleys. Next Saturday and
onward, most model guidance show either weakening of the ridge, or
progression of the ridge into the interior US causing temperatures
to cool down slightly but without a significant pattern change until
at least the following week.

Meanwhile, a surface high pressure will develop over Colorado on
Sunday behind the broader trough throughout the eastern US, driving
a modest 10-15 mb pressure gradient between Southern California and
the interior US. Offshore (E/NE) Santa Ana winds pick up Sunday
afternoon through the passes, then expand to coastal slopes Monday,
remaining elevated through at least Thursday as long as the surface
gradient persists. During this period, wind gusts of 30-45 mph,
locally up to 50 mph are possible each day for the passes and
coastal slopes. The intensity of the winds will vary slightly day to
day and will be generally strongest in the mornings. Daytime
humidities inland will drop into the 10-20% range during the
afternoons, only recovering into the 30-40% range at night. In the
case that the ridge weakens or moves east by the end of the week,
onshore winds may prevail again Saturday onward.

&&

.AVIATION...
062030Z....Low clouds/fog have the potential to develop along the
immediate coast after 03Z Sun. Chances are 10-20% in San Diego
County through 12Z Sun and 20-30% in Orange County through 19Z.
Areal coverage of any low clouds/fog will be patchy with bases less
than 500 ft and visibility 1 mile or less. Confidence is not high
enough in VIS restrictions to include fog in the TAFs at coastal
sites at this time. VFR conditions will prevail for inland areas
through the TAF period.

&&

.MARINE...
There is a 10-20% chance of dense fog with visibility 1 nautical mile
or less developing overnight tonight into Sunday morning.

&&

.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...Westerink
AVIATION/MARINE...CO