6800ft. 
687
FXUS66 KSGX 180934
AFDSGX
Area Forecast Discussion
National Weather Service San Diego CA
234 AM PDT Thu Jun 18 2026
.SYNOPSIS...
A weak low pressure system moving to near the West Coast will
spread cooling inland with high temperatures for Friday and
Saturday as much as 5 to 10 degrees below average for the
mountains and valleys. Night and morning low clouds will spread
inland across most of the valleys late each night. Southwest to
west winds during the afternoon and evening for the mountains and
deserts will be strongest on Friday with gusts to 30 to 40 mph
with gusts to 55 mph in the northern Coachella Valley below the
San Gorgonio Pass. There will be a warming trend for next week.
For Wednesday and Thursday of next week, there could be widespread
major HeatRisk for the deserts and moderate HeatRisk for other
non-coastal areas.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
...UPDATED AVIATION DISCUSSION...
.SHORT TERM (Today through Saturday)...
A weak low pressure system over the eastern Pacific will move to
near the West Coast on Saturday. It will maintain stronger onshore
flow and a deeper marine layer into Saturday. Night and morning
low clouds will spread inland across most of the valleys late each
night. High temperatures for Friday and Saturday will be near
average at sea level to as much as 5 to 10 degrees below average
for the mountains and valleys. High temperatures for Friday and
Saturday will range from the lower 70s near the coast to the
upper 70s to mid 80s for the Inland Empire with 102 to 106 for the
lower deserts. Southwest to west winds during the afternoon and
evening for the mountains and deserts will be strongest on Friday
with gusts to 30 to 40 mph and with gusts to 55 mph in the
northern Coachella Valley below the San Gorgonio Pass.
&&
.LONG TERM (Sunday through Wednesday)...
Low pressure near the West Coast will weaken with high pressure
over northern Mexico strengthening and expanding into the
southwest states. The currently forecast 500 mb temperatures for
San Diego for next Wednesday exceed the 90th percentile and would
be near record levels. High temperatures will warm for Sunday
through Wednesday with the greater warming on Monday and Tuesday
and for the mountains and valleys. NBM 90th percentile high
temperatures for next Wednesday range from the 70s near the coast
to the 90s to 104 for the Inland Empire with 114 to 118 for the
lower deserts.
Using NBM 90th percentile high and low temperatures for Tuesday
through Thursday of next week would result in widespread major
HeatRisk for the deserts for Wednesday and Thursday of next week
and widespread moderate HeatRisk for the inland valleys, mountain
elevations below 6000 feet, and inland Orange County.
Toward the end of next week, cluster analysis shows that the key
to just how warm it gets and stays is dependent on the strength of
low pressure near the Pacific Northwest coast. For Thermal for
Friday and Saturday of next week, the NBM 10th percentile high
temperatures are 109 and the 90th percentile 118. That`s more than
5 degrees above average to around 15 degrees above average. Weaker
low pressure near the West Coast toward the end of next week would
allow the inland heat wave to at least persist if not also
strengthen.
As high pressure aloft strengthens, the marine layer will decrease
in depth. The farthest overnight inland spread of coastal low
clouds will be limited to the western valleys by the middle of
next week.
&&
.AVIATION...
180930Z...Coast/Valleys...Low clouds 1800-2400 ft MSL currently
impacting coastal areas will move to cover most of the coastal basin
by 12Z. Clouds will scatter for valleys 15-18Z and coastal regions
16-20Z. 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 30%
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...17
AVIATION/MARINE/BEACHES...CSP
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