584
FXUS66 KSGX 172041
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
141 PM PDT Tue Jun 17 2025

.SYNOPSIS...
High pressure will dominate the region through Wednesday leading
to continued hot weather for inland areas. An area of low pressure
will spreading cooling across our area starting Thursday into the
weekend. By the weekend, high temperatures will be near 5 to 10
degrees below normal with a deeper marine layer. The cooler
weather pattern will continue into early next week as a trough
lingers over our area.

&&

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

.SHORT TERM (Through Friday)...
Clear skies were seen across SoCal early this afternoon as high
pressure strengthens over the southwestern U.S. Another day of warm
weather is occurring away from the coast with current temperatures
in the 80s and 90s across most valley locations with highs near 110
degrees in the Coachella Valley. High pressure will peak in
intensity on Wednesday, where 850 mb temperatures are expected to
reach near 30C. This will lead to continued hot weather for inland
areas. High temperatures have been increased by a few degrees for
some western valleys to accommodate for this warming trend, where
highs are in the 90s for inland valleys of San Diego and near 100
degrees for the Inland Empire. The high desert will also see the
hottest temperatures of the week on Wednesday as well, with a
moderate to high chance in seeing temperatures hit 105 degrees or
higher. The strong area of high pressure will continue to lead to
a suppressed marine layer, where only patchy low clouds are
expected across San Diego by early morning on Wednesday.

A trough of low pressure will move into the Pacific Northwest on
Thursday, where its influence will begin to be felt by this time.
This will bring greater onshore flow and cooling to the region, with
most inland areas lowering another 5 degrees from Wednesday. The
area of low pressure is expected to plunge southward by Friday into
the weekend, with highs cooling another 3 to 5 degrees.
Lowering pressure heights will also help build the marine layer with
low clouds and patchy fog coming back to coastal areas and western
valleys by the end of the work week.

&&

.LONG TERM (This Weekend and Beyond)...
The trough axis of the area of low pressure will move through SoCal
over the weekend. This will bring the coolest weather of the week by
Saturday, where inland temperatures will be another 5 to 10 degrees
cooler from Friday. On Saturday, we can expect highs in the 70s and
80s for all areas expect the high deserts which will stay near 100
degrees and the beaches sticking into the upper 60s. A series of
weak waves across the northern Rockies will keep the troughing
pattern in place, keeping the below average temperatures around into
early next week. Dry conditions will continue across the region for
the long term period with mostly clear skies for the mountains and
deserts and marine layer clouds each night and morning west of the
mountains.

&&

.AVIATION...
172030Z....Coast/Western Valleys...Mostly clear skies through the
evening. Areas of low clouds will develop after 05Z with bases 500-
800 feet MSL and vis 3-5SM in BR, but locally 0-2SM on higher
terrain. Scatter out Wednesday 14-16Z.

.Inland Valleys/Mountains/Deserts...Clear skies and unrestricted VIS
through Wednesday.

&&

.MARINE...
No hazardous marine conditions are expected through Sunday.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 8 PM PDT Wednesday for Orange County Inland
     Areas-Riverside County Mountains-San Bernardino and
     Riverside County Valleys-The Inland Empire-San Diego County
     Mountains-San Diego County Valleys-Santa Ana Mountains and
     Foothills.

PZ...None.

&&

$$

PUBLIC...APR
AVIATION/MARINE...MM