Spring Valley Lake, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

646
FXUS66 KSGX 130454
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
854 PM PST Fri Dec 12 2025

.SYNOPSIS...
High pressure will continue to dominate the region over the next
week, bringing warmer than average weather with minor day to day
changes. This will keep the marine layer thin, 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...

A high temperature record was broken today at Campo.
Interestingly, Borrego Springs tied both the high max temp and the
high min temp records today. Check out our record report for the
deets. Meanwhile, we`re keeping a close eye on our coastal fog
situation. A dense fog advisory is in effect through 10 AM
Saturday. While much of the coast has some fog, most of it is not
dense, at least initially; visibilities are merely 2-5 miles as
of 8 PM. There is medium to high confidence the near surface
inversion of our marine layer will work its magic to eventually
produce dense fog right on the deck overnight. Enjoy the non-
hazardous driving conditions for now, but prepare for very low
visibility later tonight into Saturday morning.

The most subtle of changes are expected in coming days. Our high
pressure aloft that has brought us such anomalous (in some cases
record-breaking) warmth, is going to break down very slightly through
Sunday night. This should keep temps rather static this weekend,
especially west of the mountains, and could deepen our marine
layer slightly, despite some very weak offshore flow. On Monday
and Tuesday the ridge makes a brief return, along with some very
weak offshore flow. That should allow temps to rebound by a few
degrees and encourage the coastal fog to retreat again.

.Previous discussion (146 PM Friday)...
The ongoing active troughing pattern in the Gulf of Alaska and
off the Pacific Northwest will begin to weaken this area of high
pressure by the middle and end of next week. This will bring
greater onshore flow and subtle cooling to our region, but dry
weather will continue. Long-range ensemble models increase chances
for the trough to push further south, where chances for
precipitation may increase toward the Christmas holiday.

&&

.AVIATION...
130330Z...Coast/Valleys...Patchy low clouds with bases around 500-
800ft MSL are already beginning to push inland, with spread up to 10
miles by 10z. VIS generally 2-6SM but periods of 1/2SM-1SM possible
for both coastal and valley areas, primarily from 05z-09z, with
VV002. Very localized areas of full obscurations of 0-1SM in FG. VIS
restrictions begin to improve after sunrise, and low clouds and FG
scatter out by 17-18z for San Diego County, with Orange County
seeing clouds linger until 18-20z. Another round of low clouds/FG
beginning around 02z Sun, with similar bases to tonight.

Mountains/Deserts...SKC and VFR conditions expected through
Saturday. High clouds AOA 20,000ft MSL into Saturday.

&&

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

PZ...None.

&&

$$

PUBLIC...MM
AVIATION/MARINE...Zuber