Bonsall, California Weather Forecast Discussion

940
FXUS66 KSGX 301613
AFDSGX
Area Forecast Discussion
National Weather Service San Diego CA
913 AM PDT Tue Sep 30 2025
.SYNOPSIS...
A low pressure trough moving inland along the West Coast will
bring cooling today, with coastal low clouds extending inland onto
the lower coastal mountain slopes this morning as the marine layer
deepens. This will be followed by warming for Wednesday and Thursday,
but with high temperatures remaining below average. Another low
pressure system will move inland through California on Friday with
cooling of a few to around 5 degrees and slight additional cooling
for inland areas on Saturday. Then mostly slight day to day differences
for Sunday and Monday with high temperatures remaining at least a
few degrees below average.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
This morning, the marine layer is about 4500 ft deep and low
clouds cover most of the area west of the mtns...including the
foothills and coastal mtn slopes. Large breaks in the low clouds
are appearing at this hour but complete clearing is unlikely due
to the strength of the inversion.
A low pressure trough moving inland today will bring stronger onshore
flow and dry southwest flow aloft. Today will be several degrees
cooler than yesterday, with inland temperatures as much as 10
degrees below seasonal averages.
For Wednesday and Thursday, the low pressure trough will move
inland and weaken. High pressure to the south will briefly
rebound, bringing warmer conditions with the marine layer
becoming a little shallower. High temperatures will warm a few
degrees on Wednesday and a few more degrees on Thursday but high
temperatures will remain around 4-7 degrees below average. High
temperatures on Thursday will range from the lower 70s near the
coast to the lower to mid 80s for the Inland Empire and the low
to mid 90s for the lower deserts.
For Friday into early next week...A low pressure system from the
Gulf of Alaska will move into CA with a closed upper low over
northern/central CA by Friday morning. The closed low will move
east and become an open wave by Sunday. This will bring general
cooling with temperatures about 5 degrees lower on Fri and further
cooling for Sat. Current indications are that Monday will be the
coolest day with temperatures as much as 10-12 degrees below
seasonal averages in the inland valleys. This system will also
bring a deeper marine layer and stronger onshore flow. Gusty
westerly winds will be likely for Friday into Saturday, mainly in
the mtns and adjacent desert areas. We will remain under the
influence of low pressure troughing through early next week,
although the forecast details will be less certain after Sat as
model solutions begin to diverge significantly.
&&
.AVIATION...
301500Z....Coasts/Valleys...Areas of thin low clouds based 3500-4500
feet MSL across the coastal basin. Scatter out expected 17-19Z. Low
clouds to redevelop after 04Z this evening, but in patchy, random,
and intermittent fashion, and less extensive into the inland valleys
by early Wednesday. Bases should be 1200-2000 feet MSL.
Mountains/Deserts...Mostly clear and VFR conditions today and
tonight.
&&
.MARINE...
No hazardous marine conditions are expected through Saturday.
&&
.BEACHES...
South swell will continue to produce elevated surf and a high rip
current risk through this evening. Surf of 3-6 feet with sets 7 feet
expected on south facing beaches. Strong longshore currents will
impact all beaches. Surf will slowly diminish today and tonight.
More information can be found in the Beach Hazards Statement.
&&
.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 this evening for Orange County
     Coastal Areas-San Diego County Coastal Areas.
PZ...None.
&&
$$
PUBLIC...PG
AVIATION/MARINE/BEACHES...Westerink

NWS SGX Office Area Forecast Discussion