Foothill Ranch, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

162
FXUS66 KSGX 150502
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
902 PM PST Sun Dec 14 2025

.SYNOPSIS...
Areas of dense fog on the coastal mesas and western valleys again
tonight into Monday morning. Well above normal high temperatures
through Thursday, with periods of weak offshore flow. Gradual
cooling with more widespread night and morning low clouds and fog
for Friday into next weekend.

&&

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

Satellite and ground observations at 9 PM were showing areas of low
clouds and fog for the San Diego coast and valleys. Visibility had
fallen to a quarter mile in a few locations. Patchy dense fog is
expected to continue into Monday morning most likely in the
valleys. Low clouds and fog become unlikely for Monday night into
Tuesday with a brief uptick in offshore winds. Highs on Monday
are expected to be a few degrees warmer than today for most
locations.

From Previous Discussion Issued at 2 PM December 14...

High pressure aloft begins to build in from the west and offshore
flow develops on Monday, with winds gusting to around 30 mph below
the passes and canyons. Weak offshore flow under high pressure aloft
will persist into Tuesday and mitigate or nullify the influence of
the marine layer so that low clouds and fog are unlikely to return
for Mon night/Tue morning or Tue night/Wed morning. It will also
bring drier and warmer conditions into the coastal areas, resulting
in daytime high temperatures on Tuesday as much as 10 degrees above
seasonal averages in the coastal areas, and up to 20 degrees above
average in the far inland valleys. Tuesday is likely to be the
warmest day overall, with high temperatures reaching the 80s in the
inland valleys and lower deserts.

Onshore flow returns on Wednesday as a shortwave trough moves inland
to the north and the upper level ridge weakens and flattens out.
This could bring some cooling to the coastal areas and far western
portions of the inland valleys, and potentially a return of low
clouds and fog to the coastal areas Wed night. However, this is a
fast-moving trough and offshore flow quickly returns on Thursday as
a sfc high follows the departing trough into the Great Basin. The
offshore winds will bring drier and warmer conditions but are
unlikely to be strong enough to produce any other impacts.

As we approach next weekend, a more vigorous trough will displace
the upper high to the south, establishing a high-zonal pattern over
CONUS. This pattern is expected to bring a weak atmospheric river to
central and northern CA next weekend but SoCal will likely remain
dry but cooler with more of a marine layer presence as onshore flow
returns. Temperatures for next Sat and Sun will range from near
normal at the coast to about 10 degrees above normal in parts of the
inland valleys.

&&

.AVIATION...
150330Z...Coast/Valleys...Low clouds have sufficiently pushed around
10 miles inland for San Diego County, and continue to spread north
into Orange County. Bases currently 600-800ft MSL, may fall closer
to 400-700ft MSL over the next few hours. VIS generally 3-6SM, but
will be down to 1-2SM for coastal terrain and valleys. Periods of
VIS down to 1/4SM in FG possible for more elevated sites, especially
after 08z. Clouds and FG may clear a bit quicker Monday morning with
offshore flow returning, possibly as early as 14z. Clouds are
expected to linger at sites closer to the coastline, including KSAN,
through 18-19z.

Mountains/Deserts...Clear skies and VFR conditions expected through
the Monday evening.

&&

.MARINE...
Low clouds will bring areas of low visibility around 2-5 nautical
miles through early Monday afternoon. 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...CO/PG
AVIATION/MARINE...Zuber