631
FXUS66 KSGX 131102
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
302 AM PST Sat Dec 13 2025

.SYNOPSIS...
High pressure will continue to dominate the region over the next
week, bringing high temperatures well above normal with minor day
to day changes. The marine layer remains shallow, leading to low
clouds and fog near the coast, where the fog may be locally dense
over the next couple of nights/mornings.

&&

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

Low clouds and fog have spread will inland in Orange County, but
remain confined to the coast in San Diego County. Expect clouds
and fog to spread slightly further inland in San Diego County,
clearing over land by late morning. Fog will be dense at times,
and the Dense Fog Advisory continues through 10 AM for the coastal
areas. Further inland, a band of high clouds will move off to the
east through the morning before another band moves in this
afternoon. Low clouds and fog redevelop this evening, spreading
back into the coastal areas tonight. With little change in the
marine layer depth, patchy dense fog is likely to occur once
again tonight into Sunday morning.

The upper level ridge of high pressure over the region breaks down
this weekend, allowing a weak short wave trough to progress
eastward across CA. This will bring slight cooling with a return
of more predominant onshore flow through the weekend, though highs
remain 10 to 15 degrees above normal. The upper ridge rebounds on
Monday and Tuesday, combining with another round of weak Santa
Ana winds to bring warming with highs locally up to 20 degrees
above normal. Winds won`t be particularly strong, remaining
confined to the usual passes, canyons, and coastal slopes where
peak gusts will be around 30 mph. Enough of an offshore push of
drier air could occur to rid of us the marine layer low clouds and
fog.

The upper high slowly weakens and onshore flow returns for the
latter half of the week. There are subtle differences in the
ensembles with how much the ridge weakens and is replaced by zonal
flow, especially as we head into the end of the week. Around 60%
of the ensemble members show zonal flow and therefore more
cooling, while the remaining 40% maintain weak ridging for warmer
weather. Either way, precipitation chances are zero through
Friday. Ensembles are definitely trending wetter for next week, so
we`ll see if that holds.

&&

.AVIATION...
130930Z...Coast/Valleys...Patchy low clouds with bases around 200-
600 ft MSL starting to move into inland Orange County and still
developing into coastal SD County. VIS generally 2-6SM  due to BR/HZ
but periods of 1/2SM-1SM in FG for both coastal and valley areas
through around 17z. Low clouds scatter out and VIS improves by 17-
18z for San Diego County, with Orange County seeing clouds linger
until 18-20z. Low clouds/FG return around 02z Sun, with similar
bases and VIS reduction to this morning, with a slightly greater
inland extent.

Mountains/Deserts...SKC and VFR conditions expected through
early Sunday.

&&

.MARINE...
Patchy fog will continue, improving late this morning. Visibility
reductions to 1 NM or less at times. A Marine Weather Statement is
in effect until noon Saturday for the impacts from fog and contains
more details. 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...Dense Fog Advisory until 10 AM PST this morning for Orange
     County Coastal Areas-San Diego County Coastal Areas.

PZ...None.

&&

$$

PUBLIC...SS
AVIATION/MARINE...Westerink

NWS San Diego (SGX) Office