055
FXUS66 KSGX 181824
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
1124 AM PDT Thu Jun 18 2026

.SYNOPSIS...
Below average temperatures with marine layer low clouds and fog
reaching into portions of the valleys through Sunday. Gusty westerly
winds expected in the mountains and deserts this afternoon and
evening and again Friday afternoon and evening. Warming trend
expected Monday through at least the middle of next week. Areas of
major HeatRisk possible for the deserts and moderate HeatRisk for
inland Orange County, valleys, and mountains mid next week. The
marine layer will become shallower next week, staying confined to
coastal locations.

&&

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

Visible satellite this morning showed marine layer low clouds and
fog had completely filled in the coastal basin, even filling in the
Cajon Pass. The 12Z KNKX sounding showed a hefty inversion of 11
degrees Celsius, which will make for slow clearing today especially
for the coast. The marine layer is expected to be a similar depth
tonight into Friday morning. Patchy drizzle may develop along the
coast, but confidence is not high enough in widespread drizzle to
add to the official forecast. The marine layer will stay fairly deep
through the weekend, reaching into the valleys each night and
morning.

High temperatures through the weekend will be below average for most
locations due to a passing trough. In addition to cooler conditions
(and the deeper marine layer), elevated southwest to west winds can
be expected. Winds during the afternoon and evening for the
mountains and deserts will be strongest on Friday with gusts 30 to
40 mph and with gusts to 55 mph in the northern Coachella Valley
below the San Gorgonio Pass.

By Tuesday, an upper level area of high pressure will have built
into the desert southwest. This will shrink the marine layer and
result result in 3 to 5 degrees of warming between Monday and
Tuesday. Through the week, the high will drift west. This will bring
above average conditions to inland areas. Current forecast follows
the NBM for Tuesday through next Thursday which will bring high
temperatures 5 to 10 degrees above average with areas of moderate
HeatRisk away from the coast and areas of major HeatRisk in the low
desert. Hottest conditions based on current forecast are expected to
be Wednesday and Thursday. Ensemble guidance is also indicating an
increase in precipitable water for the middle to end of next week.
That would result in warmer than normal overnight low temperatures
and a disrupted marine layer limiting low cloud development.

The spread in potential forecast solutions starts to increase for
the middle to end of next week. Ensembles are indicating the
possibility of a shortwave trough moving through California, which
would result in a few degrees of cooling if it verifies. Right now
the solutions are split fairly equally for Thursday with 51 percent
of solutions bringing in the shortwave trough and 49 percent keeping
the ridge aloft. If the ridging were maintained, that would prolong
the above average conditions into the end of next week. Any increase
in high or low temperatures above current forecast will likely
result in more widespread moderate or major HeatRisk, especially
for the end of next week. We`ll continue to monitor forecast
trends in the coming days.

&&

.AVIATION...
181758Z...Coast/Valleys...Low clouds 1800-2800 ft MSL with Tops to
near 3500 feet clearing back to the coastal areas. There will likely
be some localized low clouds lingering along parts of the coast
through most of the afternoon, highest chances in southern San Diego
County vcnty La Jolla. There is a 60% chance KSAN could only
partially/intermittently clear. Clouds with similar bases will
become more widespread and move back into coastal regions after 00Z
Friday, then back to cover most of the coastal basin again by 12Z
Friday.

Mountains/Deserts... VFR conditions. Breezy westerly winds gusting
25-30 kts through mountain passes and into deserts 18Z through 09Z
Friday. There could be temporary VIS restrictions due to FU
(wildfire smoke) in an around the Coachella Valley area through
Thursday evening.

&&

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

&&

.BEACHES...
Elevated surf and strong rip currents continue through Friday. Surf
of 3-5 feet with local sets to 6 feet are expected at south-facing
beaches. Surf for southern San Diego County will be slightly lower,
but hazardous swimming conditions with high rip current and
longshore current risk will still exist. See the Beach Hazards
Statement for more details.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through Friday evening for Orange County
     Coastal Areas-San Diego County Coastal Areas.

PZ...None.

&&

$$

PUBLIC...CO
AVIATION/MARINE/BEACHES...Small

NWS San Diego (SGX) Office