145
FXUS66 KSGX 101636
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
836 AM PST Wed Dec 10 2025

.SYNOPSIS...
High temperatures will continue to warm for inland areas today,
to around 20 degrees above average for portions of the inland
valleys with locally gusty Santa Ana winds to 35 mph near the
coastal slopes of the mountains through this morning. Cooling for
the coast and valleys on Thursday and Friday will spread inland
over the weekend as high pressure aloft weakens and weak onshore
lower-level flow returns. A shallow marine layer will return for
Thursday and Friday with night and morning coastal low clouds
spreading locally into the western valleys over the weekend as the
marine layer slowly deepens. High temperatures will be coolest on
Sunday and Monday, but still 10 to 15 degrees above average for
inland areas.

&&

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

.Morning Update...

Light offshore winds continue across coastal facing slopes and
passes near 20-30 MPH, with other areas seeing calmer winds. These
winds will continue to be persistent throughout much of the day.
We continue to expect the warmest temperatures to occur by this
afternoon with moderate to high confidence in seeing high
temperatures reach 85 degrees or more across parts of the Inland
Empire and San Diego County valleys. Highs look to reach near 80
degrees across the lower deserts as well as within a few miles of
the coastline. Some places may break record daily highs today,
including Chula Vista, Riverside, Ramona, Palomar Mtn, and Borrego
Springs. The forecast remains on track to show a subtle cooling
trend into the weekend with dry weather expected for at least the
next week.

.Previous Discussion (315 AM Wednesday)...

.SHORT TERM (Today through Friday)...
High temperatures for inland areas will continue to warm today, to
around 20 degrees above average for portions of the inland valleys
and lower coastal mountain slopes, while coastal areas cool a few
degrees. High temperatures for today will range from the lower
to mid 70s near the coast to the 80s for the valleys with the
lower to mid 80s for the lower deserts. Northeast winds along and
below the coastal slopes of the mountains into this morning will
locally gust to 35 mph.

Greater cooling of a few to around 5 degrees will spread into the
coast and valleys on Thursday as weak onshore flow and a shallow
marine layer returns. High temperatures on Friday will be a few
degrees cooler for the coast and valleys with not much change for
the deserts. High temperatures on Friday will range from the mid
to upper 60s near the coast to the mid 70s to lower 80s for the
valleys with the lower to mid 80s for the lower deserts.

Some patchy low clouds and locally dense fog could return near the
coast Thursday night into Friday morning with a more likely return
along with increasing coverage of low clouds and fog for Friday
night into Saturday morning.

&&

.LONG TERM (Saturday through Tuesday)...
Slow cooling will continue to spread inland for Saturday and
Sunday with not much change on Monday as weak onshore flow
continues and the marine layer slowly deepens. Night and morning
coastal low clouds will increase in coverage over the weekend and
may locally extend inland into the far western valleys.

Even with the cooling, high temperatures for inland areas on
Sunday and Monday will still be around 10 to 15 degrees above
average for inland areas, ranging from the mid to upper 60s near
the coast to the mid to upper 70s for the inland valleys with the
lower deserts around 80.

For the middle and latter part of next week, the calibrated
deterministic NBM continues to show slowly warming high
temperatures, but with increasing spread in the high temperature
guidance due to increasing spread in the strength of high pressure
aloft along the West Coast. For Ontario, the spread between the
25th and 75th percentile of the high temperature guidance
increases from as little as two degrees for today through Friday
of this week, to 10 degrees for Thursday and Friday of next week.

&&

.AVIATION...
101630Z...Clear skies with continuing VFR conditions expected
through the TAF period. Winds continue to be a bit breezy in the
foothills and locally adjacent valleys with areas of northeast
winds gusting 25-30 kts through 22Z. There is a small chance for
some patchy fog along the immediate coast beginning around 05Z
Thursday but confidence isn`t high enough that conditions would
fall below VFR to include in the TAFs at this time.

&&

.MARINE...Patchy, intermittent fog development possible after
midnight tonight which could reduce local visibility below 1 NM at
times through Friday morning. Otherwise, no hazardous marine
conditions are anticipated through Sunday.

&&

.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.

&&

$$

UPDATE...APR
PUBLIC...17
AVIATION/MARINE...Villafane

NWS San Diego (SGX) Office