211
FXUS66 KSGX 050024
AFDSGX
Area Forecast Discussion
National Weather Service San Diego CA
524 PM PDT Sun Oct 4 2026
.SYNOPSIS...
High pressure remains over the region, bringing a prolonged period
of hot weather, most notable west of the mountains. Breezy Santa Ana
winds will continue through Monday; highest winds will be near the
coastal-facing mountain slopes with an elevated fire weather risk.
Confidence is increasing that cooler weather enters the picture by
the end of the week, but details in how cool we become and if any
wet weather arrives is still uncertain.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
...UPDATED AVIATION DISCUSSION...
Weaker Santa Ana winds have been observed this morning, mainly below
35 MPH. This pattern has contributed to very hot temperatures
this morning for areas west of the mountains. Valley and coastal
locations are close to 95-100 degrees. Subtle increases in onshore
flow and a weakening of the high pressure system overhead will
allow increased onshore flow closer to the coast, bringing a few
degrees of cooling each day. By Wednesday, confidence starts to
increase to see highs below 100 degrees for the valleys and
coastal areas of Orange and San Diego Counties. 850mb temperatures
increase by Wednesday and Thursday with a thermal ridge poking
into the Desert Southwest, leading to an increase in temperatures
over the mountains and deserts a few degrees from what we have
seen this weekend. Nights will still remain warm for many areas in
the lower to mid 70s for the lower deserts and places west of the
mountains. Please make sure to be in areas of A/C and check on
those without effective cooling.
Models begin to diverge on our next story starting Friday into next
weekend. Cluster analysis starts to break down the ridge on Friday,
leading to greater onshore flow and cooling for places from the
foothills to the coast. Highs for coastal areas and valleys will
lower mainly into the 80s and 90s by this time with a better chance
to see lows below 70 degrees.
As the ridge weakens, a trough is expected to enter the PacNW around
Friday or Saturday. Model guidance is continuing to struggle on
where exactly this weather system progresses and how amplified it
becomes. A deeper trough across California would lead to more
significant cooling next weekend with some model ensembles showing
light amounts of precipitation around Sunday or the following
Monday (October 12th). Others show the trough staying further
north, which would still bring cooler weather, but keep us on the
drier side. Would not be surprised to see a sort of mesh between
these depictions to the forecast in the coming days, where cooler
weather arrives but dry conditions continue.
&&
.AVIATION...
050000Z...Coast/western valleys: SKC and VFR through the period.
Moderate to high confidence for typical onshore W/NW winds through
late Monday morning and afternoon.
Inland Valleys/Foothills/Mountains: Westerly and easterly winds
converging over the foothills to weaken by 03z. Easterly flow
increases again slightly after 10z over west facing foothills and
eastern valleys, gusting to 15-25 kts, turning westerly once again
over the eastern valleys Monday afternoon. MOD UDDFS expected over
coastal slopes. Otherwise...Clear skies through the TAF period.
&&
.MARINE...
No hazardous marine conditions are expected through Thursday.
.BEACHES...
A 4-5ft 12-13 second South swell arrives in Southern California
Tuesday afternoon. Elevated surf of 3-6 feet on south and southwest-
beaches expected. High tides are expected to peak between 6.5 and
7.0 feet during the morning and evenings. In combination with the
elevated surf, minor coastal flooding and beach erosion will be
possible during high tides through the end of the week.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Extreme Heat Warning until 8 PM PDT Thursday 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.
Beach Hazards Statement from Tuesday afternoon through Friday
evening for Orange County Coastal Areas-San Diego County
Coastal Areas.
PZ...None.
&&
$$
PUBLIC...APR
AVIATION/MARINE/BEACHES...Westerink NWS SGX Office Area Forecast Discussion