San Diego Weather at Mission Trails, CA

772
FXUS66 KSGX 162113
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
213 PM PDT Sun Aug 16 2026

.SYNOPSIS...
Slight chance of showers over the San Bernardino Mountains this
afternoon. Upper level high pressure will slowly build in from
the east this week, bringing gradual warming, a shallower marine
layer, and dry weather. Shower and thunderstorm chances return for
the mountains Thursday through Saturday with subtle cooling as
the upper high shifts east.

&&

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

Current temperatures are running a few degrees warmer than
yesterday inland, though still generally near or slightly below
average for this time of year. High based cumulus have developed
over the mountain ridges, but are struggling to develop into deep
vertical clouds at this time. A similar inversion at 15,000 feet was
observed in yesterdays sounding and cells were able to develop later
in the afternoon despite this. A shower or thunderstorm can thus not
be ruled out this afternoon locally over the highest peaks of the
San Bernardino County and Riverside County mountains. The marine
layer is about 3000 feet deep as of this morning and is expected to
become slightly shallower into the middle of the week. Patchy fog
expected during the nighttime hours in inland valley spots where
clouds intersect terrain.

The broad center of the 500mb ridge drifts into the Desert Southwest
this week, increasing temperatures a few degrees per day through mid-
week. High temperatures for inland areas likely peak Thursday (90s
to low 100s), with similar temperatures lingering through at least
the weekend. Through the forecast period, lower desert temperatures
largely appear unaffected by the ebb and flow of the ridge, with
highs consistently 108-111F throughout the week.

As the center of the ridge migrates toward the Four Corners region,
southeasterly flow will bring increasing mid-level moisture and
shower/t-storm chances for the mountains through Saturday. Beyond
Saturday, model clusters diverge into two general solutions: a
ridge over the Northwest, which would keep the warmer than average
temperatures around, and a ridge over the Central US, which could
return temperatures back to near average.

&&

.AVIATION...
161735Z....Coast/Valleys...Low clouds will mostly remain off the
coast through the early evening hours. Confidence increasing on a
later time period for low clouds to impact coastal TAF sites. Low
clouds near 1300-1700 ft MSL will move ashore in San Diego County
after 04Z, closer to 07Z in Orange County. Cig impacts may be
intermittent at KSNA. Low clouds clearing to the coast 15-17Z Mon.

Mountains/Deserts...VFR conditions prevail through the TAF period.
SCT-BKN cu AOA 10,000ft MSL building into the afternoon with a
slight chance (10-20%) for TSRA over the Riverside and San
Bernardino county mountains. Cu dissipates this evening with high
clouds moving in from the west. Chance of rainfall nil on Monday.

&&

.MARINE...
Gusty northwest winds 20-23 knots near San Clemente Island expected
this afternoon and Monday afternoon. Otherwise, no hazardous marine
conditions are expected through Thursday.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.

&&

$$

PUBLIC...Westerink
AVIATION/MARINE...APR