767
FXUS66 KSGX 140959
AFDSGX
Area Forecast Discussion
National Weather Service San Diego CA
259 AM PDT Sat Mar 14 2026
.SYNOPSIS...
Cooler this weekend with a return of the marine layer at the
coast. Gusty west winds in the mountains and deserts this
afternoon will transition to weak offshore flow Sunday through
Tuesday. Significant warming Sunday through Friday with high
temperatures of 20 to 30 degrees above normal and moderate to
high heat risk.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
Scattered high clouds are moving across the region this evening
with no signs of marine layer clouds nearby. A weak upper level
trough moving by to the northeast will bring an increase in
onshore flow today. Breezy west winds will develop across the
mountains and deserts this afternoon with gusts around 30-40 mph,
locally higher below the San Gorgonio Pass. This trough and a
developing coastal eddy will spread cooling inland today, though
highs will still be around 10-15 degrees above normal. Marine
layer low clouds are forecast to develop over the coastal waters
this afternoon, spreading into the coastal areas this evening into
Sunday morning. Fog may be dense at the coast when the marine
layer first rebuilds, shifting onto the coastal mesas tonight as
the marine layer deepens.
The trough makes a quick exit and surface pressure gradients turn
offshore by Sunday morning. Winds will be confined to the usual
passes and canyons with peak gusts around 25-35 mph. The big story
is how this will begin our warming trend as offshore flow combines
with the upper level ridge amplifying off the West Coast. For
Sunday, high temperatures will increase to around 15-20 degrees
above normal, with the greatest departure from normal in the
valleys. Offshore flow weakens for Monday and Tuesday, but the
ridge slowly shifts eastward over CA. This will result in warming
for all areas, and by Tuesday highs will be approaching 30 degrees
above normal in the Inland Empire, and around 20-25 degrees above
normal elsewhere.
The ridge continues to slowly drift eastward for the latter half
of the week, becoming centered near the lower Colorado River
Valley and strengthening. Friday is currently forecast to be the
hottest day of the week with high temperatures around 30 degrees
above normal away from the coast, and around 20 degrees above
normal at the beaches. This translates to highs in the mid 80s at
the beaches, low 90s to 105 for the inland coastal areas and
valleys, low 80s to low 90s in the mountains, upper 90s in the
high deserts, and 109-112 in the low deserts. Moderate to locally
high HeatRisk exists for most areas by Thursday and Friday,
becoming High in the low deserts late in the week. Current Extreme
Heat Watches may need to be expanded to include parts of the
mountains and the low desert at least Thursday and Friday,
possibly into Saturday. Many March temperature records are likely
to be broken late in the week. See the CLIMATE section for more
details.
&&
.AVIATION...
141200Z...VFR conditions with SCT high clouds expected today.
Satellite shows patchy low clouds (near 300-500ft MSL) out over the
waters, but quite offshore and south of the International Border.
Aided by a developing coastal eddy, guidance suggests these clouds
will gradually increase in coverage and spread northward over the
next several hours. This brings a window (14-17z) for CIGs and
reduced VIS (down to 2-4 SM), mainly at KSAN, but there is only
about a 20-30% chance of this occurring. Next to 0% chance for any
impacts at KCRQ or KSNA.
Any clouds that may sneak ashore later this morning will retreat
offshore by 17z, but the coastal eddy should continue to increase
cloud cover over the waters into the afternoon. These clouds are
expected to lift to around 400-800ft MSL this evening, pushing
ashore after 02z Sunday.
&&
.MARINE...No hazardous marine conditions are expected through
Wednesday.
&&
.CLIMATE...
The following are the existing highest temperature records for March
for selected locations along with the highest daily NBM probability to
set a new March record for next week. This is not a comprehensive
list, but the most likely locations to tie or set new monthly
record high temperatures for March are in the deserts, valleys,
and mountains.
Location March Record NBM Probability
Palm Springs 104 95-100 percent (Wed,Thu,Fri)
Indio 104 100 percent (Wed, Thu, Fri)
Thermal 103 100 percent (Wed,Thu, Fri)
Ramona 94 92-97 percent (Thu, Fri)
Big Bear 80 100 percent (Thu, Fri)
Santa Ana 98 40-50 percent (Thu, Fri)
The existing highest 500 mb height for NKX for March is 590 DM. That
could be exceeded for multiple days next week between Tuesday and Friday.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Extreme Heat Watch from Monday morning through Friday evening
for Orange County Coastal Areas-Orange County Inland Areas-
San Bernardino and Riverside County Valleys-The Inland
Empire-San Diego County Coastal Areas-San Diego County
Valleys-Santa Ana Mountains and Foothills.
PZ...None.
&&
$$
PUBLIC/CLIMATE...SS
AVIATION/MARINE...Munyan
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