301
FXUS66 KSGX 011811
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
1011 AM PST Sun Mar 1 2026

.SYNOPSIS...
High pressure aloft is weakening and shifting east and onshore
flow has returned. Temperatures will moderate near the coast as
marine air spreads inland but record-setting heat will continue
for many inland areas today, including the low deserts. The
cooling trend will continue through Monday, but with daytime
temperatures remaining above seasonal averages. There will be
stronger and gusty west winds each afternoon and evening in the
mountains and deserts today and Monday. Gusts of 35 to 45 mph are
likely in the wind-prone areas. Dry and a little warmer for
Tuesday through Saturday.

&&

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

This morning...Skies are mostly sunny with some high clouds.
Temperatures are near to as much as 6 degrees lower west of the
mountains than at this time yesterday as onshore flow pushes
cooler marine air inland while the deserts are mostly a few
degrees warmer than yesterday. Despite the onshore flow, high
temperatures today will still be as much as 20 degrees above
seasonal averages in portions of the inland valleys, mountains and
deserts.

The axis of the upper level ridge has shifted to the east as a low
pressure system off the coast of northern CA moves toward the coast.
A weakening cold front is associated with this system and is
approaching Point Conception from the west. The band of frontal
clouds will likely move into SoCal over the next 24 hours but is
unlikely to bring any precipitation. This low pressure system will
move eastward into the Great Basin by Tuesday. It will bring more
significant cooling for Monday when daytime high temperatures
will be in the 60s and 70s west of the mtns, in the 70s in the
high deserts, the 50s in the mtns and in the upper 80s to about 90
in the low deserts. These values are still near seasonal averages
in the coastal areas but above seasonal averages elsewhere. The
onshore flow will continue to strengthen, peaking on Monday when
it will produce southwest to west winds gusting 35-45 mph in the
mountains and deserts before weakening on Tuesday. Patchy marine
layer low clouds and fog will likely return to the coastal areas
late tonight then again Monday and Tuesday nights.

Temperatures will rebound somewhat for Tuesday and Wednesday as
the low pressure trough moves into the Rockies and a weak
transient ridge of high pressure moves over the region. Daytime
high temps will again be 5 to 11 degrees above seasonal averages
with mostly sunny skies after the low clouds and fog dissipate.

Numerical models remain in good agreement into Thursday before
solutions diverge as we move into next weekend. Another low
pressure system will move inland to the north on Thursday bringing
slightly lower temperatures for Thu and Fri along with another
round of strong onshore flow on Thursday.

Forecast details become more uncertain after Thursday as the
deterministic models show a closed upper low forming near SoCal by
Saturday. These models disagree significantly on the location of
the closed upper low. While a slim majority of ensemble members
across model platforms agree (in general) with this solution, a
significant minority of ensemble members produce a solution where
the upper trough remains an open wave and continues to progress
eastward into the southern Rockies. The first solution has the
potential to produce precipitation for SoCal while the second
solution keeps us dry. For now, the forecast remain dry but stay
tuned.

&&

.AVIATION...
011800Z....Coast...VFR conditions and mostly clear skies prevail for
the first half of the period with marine layer clouds increasing
after 06z Monday. These low clouds are expected to stretch 10-15
inland, based around 400-800 ft MSL with VIS at sea level generally
3-5 SM in BR, lower VIS for coastal mesas. Scattering expected by
18z Monday.

Elsewhere...VFR with SKC-FEW250. Winds will begin to increase after
20z in the mountains and deserts with gusts up to 20-35 knots with
locally higher gusts in the mountain passes.

&&

.MARINE...
Northwest winds increase over the outer waters this afternoon
creating hazardous conditions for small craft. Peak gusts of 20 to
25 kt are expected, with seas of 4 to 7 ft. Strongest winds and
highest seas will be in the outer waters near San Clemente island.
Winds and seas will decrease Monday night into early Tuesday.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 4 PM this afternoon to 9 PM PST Monday
     for Waters from San Mateo Point to the Mexican Border
     Extending 10 to 60 nm out including San Clemente Island.


&&

$$

PUBLIC...PG
AVIATION/MARINE...Munyan

NWS San Diego (SGX) Office