160
FXUS66 KSGX 220017
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
517 PM PDT Sun Jun 21 2026

.SYNOPSIS...
Warming trend for the first half of the week brings widespread
moderate to areas of major HeatRisk possible for the deserts and
widespread minor to locally moderate HeatRisk for inland Orange
County, valleys, and mountains for Wednesday. The marine layer
will become shallower through midweek, staying confined to
coastal locations. A few stray showers/storms are possible over
the mountains on Wednesday. Gradual cooling expected for the
second half of the week with the marine layer becoming deeper.

&&

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

Current satellite and 500mb analysis reveals largely zonal flow
aloft and a weak upper ridge across northern Mexico, with marine
layer clouds clearing out to the coasts for the day. Temperatures
early this afternoon are running near to slightly warmer than
yesterday, but is still coming in 5-10 degrees below normal for most
across the region. However, today looks to be the coolest day of the
next several as model guidance remains consistent in the upper level
ridge strengthening and sliding northward over the next few days,
becoming centered near El Paso by Tuesday afternoon. The placement
of this ridge also establishes southeasterly flow aloft, allowing
for an influx of mid level moisture into the area. The ridge and the
moisture will likely serve to limit the vertical depth and inland
extent of the marine layer through midweek. The main consequence
will be the notable warming trend, that takes afternoon temperatures
5-10 degrees above normal by Wednesday. More importantly, the
moisture will inhibit overnight cooling, leading to mild nights,
with low temperatures running 5-10 degrees above normal as well and
limiting overnight relief from he warm daytime temperatures. This
brings areas of moderate HeatRisk into the inland valleys on
Wednesday, with locally major HeatRisk for the deserts.
Additionally, the increased mid level moisture could support the
development of a few showers/storms over the mountains Tuesday or
moreso Wednesday afternoon. A weak shortwave rounding the western
periphery of the ridge Tuesday into Wednesday may provide enough
synoptic support for updrafts to overcome inhibiting cloud cover and
dry air above the moist layer, but these are 2 main factors that
will likely keep any impacts from these precipitation chances little
to none.

Ensembles continue to push a longwave trough into the Pacific
Northwest for Thursday into Friday, which should help weaken the
ridge and nudge it south/east as well as kick out the mid level
moisture. This results in a cooling trend into the weekend with the
marine layer deepening again. Temperatures return to near average
for Thurs/Fri with the potential for afternoon highs 10 degrees or
more below normal for the weekend.

&&

.AVIATION...
220015Z...Coast/Valleys...Low clouds based near or just below 2000
ft MSL are expected to reform over coastal San Diego County starting
around 03z. Clouds will spread northward into Orange County
overnight and reach up to 20 miles inland by 09-12z. 30-40% chance
for clouds to reach into the southern and western Inland Empire
(including KONT). Clouds scatter to the coastline 15-18z. Low clouds
return to coastal San Diego County starting 01-03z Tue with slightly
lower bases than tonight.

A large structure fire continues to burn in Los Angeles.
Intermittent minor vis reductions (4-6SM) in FU expected for the
northern Inland Empire (KONT) and possibly for western Orange County
(KSNA).

Mountains/Deserts...VFR conditions with periods of upper level
clouds AOA 20k ft expected through the TAF period. Westerly wind
gusts of 25-40 kts along desert slopes and locally into deserts
expected through about 06-09Z Mon. Local VIS reductions 4-6 SM in
BLDU during periods of strong gusts and moderate up/downdrafts in
lee of mtns.

&&

.MARINE...
No hazardous marine conditions are expected through Thursday.

&&

.BEACHES...
Elevated surf and strong rip currents will continue through this
evening with a persistent long period southwesterly swell. Surf of 3-
5 feet with local sets to 6 feet are expected at southwest-facing
beaches. Expect locally hazardous swimming conditions with high rip
current risk. Surf heights will lower slightly by Monday, but may
become elevated again by Wednesday as fresh long-period southerly
swell moves in. Strong rip currents will remain possible through the
upcoming week. 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 until 11 PM PDT this evening for Orange
     County Coastal Areas-San Diego County Coastal Areas.

PZ...None.

&&

$$

PUBLIC...Munyan
AVIATION/MARINE/BEACHES...KW

NWS San Diego (SGX) Office