Perris, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

778
FXUS66 KSGX 151726
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
926 AM PST Mon Dec 15 2025

.SYNOPSIS...
Patchy dense fog gradually erodes from the coastal mesas and
western valleys through late this morning. High pressure and weak
offshore flow will continue to bring fair weather and above
normal temperatures through Friday, with cooler weather this
weekend. Coastal low clouds and fog will continue each night and
morning, but less inland coverage Tuesday through Thursday and more
coverage Friday through the weekend.

&&

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

Foggy conditions are present along the coast and into valleys to
about 10-15 miles inland this morning, and many weather stations
are reporting visibility between a quarter mile and 3 miles under
the stratus deck. This morning`s sounding combined with local
pilot reports reveals a saturated layer 1000-1200 feet deep.
Typically when the marine layer makes it inland like this,
visiblity improves as you approach the coast, but the deeper cloud
layer has prevented major improvements.

Between the deep cloud layer, the strong inversion present this
morning, and the shallow saturated layer present at the bottom of
the inversion that can be seen on the sounding, the cloud layer
will be later than average in retreating to the coast and will
likely stick around for parts of the beaches through the early
afternoon. Inland areas in San Diego County have been clearing
fairly well, but clouds appear more stubborn along SD coastal
areas and for most of Orange County.

While the coastal cloud layer will result in cool temperatures
this afternoon similar to yesterday`s, areas just inland are
starting a warming trend today, with afternoon high temperatures
2-6 degrees warmer today than yesterday. Otherwise, locally breezy
offshore winds will continue today and tomorrow through parts if
the mountains as well as areas south of the Cajon Pass and
through and west of the Banning/San Gorgonio Pass. Peak gusts are
generally 20-30 mph, with local gusts to around 40 mph.

.PREVIOUS DISCUSSION...224 AM PST Mon Dec 15 2025...
With a slightly deeper marine layer this morning, the dense fog is
not as widespread as it has been previously. Still, pockets of
dense fog can be expected on higher coastal mesas and western
valleys this morning, so be aware and plan accordingly, especially
if you travel on the 91 or 241 in OC into Riverside County or the
15 in San Diego County. Otherwise, look for another sunny and warm
day, especially away from the coast.

Offshore flow will increase a little today, producing localized
northeast winds through Tuesday morning in the usual foothill
areas through and below mountain passes. Isolated top gusts could
reach 30-40 mph. This offshore flow will push back on the marine
layer, reducing coverage of coastal clouds and fog for tonight and
Tuesday morning.

Our large scale weather pattern features a strong, active zonal
flow, which has brought and will bring heavy rain to WA, OR. The
next shortwave through that region will help turn flow here in
SoCal briefly onshore Tuesday night and Wednesday, bringing back
more coastal fog and also briefly boosting winds in the mountains
and deserts, particularly the high desert late Wednesday. The flow
trends offshore again Wednesday night and Thursday before turning
weakly onshore again Friday. This time the onshore flow appears
to remain for the weekend and beyond, with coastal clouds probably
reaching into some valleys nights and mornings. Temperatures will
fluctuate, especially west of the mountains, as the surface flow
oscillates from onshore to offshore and back again. Right now
Tuesday and Thursday look like the warmest days in the coming
week, with high temps inland reaching 15-20 degrees above average
for this time of year, and 5-10 degrees above average at the
coast. Even the cooler days this week will continue well above
average regionwide.

That zonal jet stream to our north will slowly but steadily sag
southward next week, tapping into some subtropical moisture along
the way. Confidence is understandably low in any forecast that far
out, but if the majority of current ensemble solutions are right,
SoCal would get some rain by the time Santa Claus arrives.

&&

.AVIATION...
151630Z...Coast/Valleys...Currently low clouds based 200-500 ft MSL
over the coast stretching inland 15 SM with BR/FG visibilities 1/4-1
1/2 SM. Clouds and fog should start clearing out around 17-18Z for
San Diego County and after 19-20Z for Orange County. Low clouds with
bases around 100-500 ft MSL and BR/FG with visibilities 1/4-3 SM are
expected to return this evening after 02-03Z for the San Diego coast
and after 05-06Z for Orange county. Low clouds and fog will be much
patchier in nature than this morning.

Mountains/Deserts...Clear skies and VFR conditions expected through
the TAF period.

&&

.MARINE...
Low clouds will bring areas of low visibility around 2-5 NM through
the early afternoon. Seas will rise briefly to 5 to 7 feet in the
outer waters Wednesday afternoon through late Thursday. Otherwise,
no hazardous marine conditions are expected through Friday.

&&

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

&&

$$

PUBLIC...CSP
AVIATION/MARINE...Villafane