Hesperia, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

506
FXUS66 KSGX 091623
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
923 AM PDT Wed Jul 9 2025

.SYNOPSIS...
Heat peaks today and Thursday for inland locations. Conditions will
return to slightly below average west of the mountains for the
weekend into next week, with above average temperatures remaining
in the deserts. A shallow marine layer with patchy low clouds and
fog near the coast Thursday morning, with a more uniform marine
layer cloud deck that will reach into the western valleys
returning for the weekend into early next week.

&&

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

Marine layer low cloud and fog coverage was patchy overnight and did
not make it much past the beaches. The high pressure aloft centered
over Arizona and New Mexico has expanded west today, allowing some
monsoonal moisture into the region. Precipitable water on the 12Z
KNKX sounding this morning was 1.08 inches. Even with the moisture
influx, dry conditions will prevail with just an increase in mid
to high level cloud coverage expected. The high will continue to
move west into Thursday, becoming more centered over Southern
California. The high pressure aloft will keep the marine layer
shallower and any additional influx in moisture will keep any
marine layer low cloud coverage patchy and confined to coastal
areas tonight into Thursday morning.

With the upper level high expanding west across Southern California
today and Thursday, above average temperatures are expected for
inland locations. Highs today and Thursday are expected to be 5 to
10 degrees above average for inland locations. High temperatures
will range from the 70s near the coast; to the 90s to 105 for the
Inland Empire; and 114 to 118 for the lower deserts. In the
mountains below 5000 ft, highs are expected to be in the mid-80 to
upper 90s. Widespread moderate HeatRisk is expected for the valleys
and mountains, with widespread major HeatRisk in the low deserts.
Make sure you`re staying hydrated, seeking shade, and avoiding
strenuous activity during the hottest parts of the day if possible.

High pressure aloft will remain over Southern California Friday into
early next week, but will weaken slightly and continue to move
westward over the Pacific. Highs on Friday are expected to be 4 to 8
degrees cooler than Thursday across the area. For the weekend into
the middle of next week, there will be minor day to day fluctuations
in highs temperatures. NBM high temperatures for the coast and
valleys are forecast to be up to 5 degrees below average with the
deserts around 5 degrees above average. The marine layer will deepen
Sunday through Tuesday with night and morning low clouds
extending inland to the western valleys through the middle of next
week.

&&

.AVIATION...
091530Z....Coast...FEW-SCT high clouds AOA 20 kft. Patchy low clouds
based 800-1100 feet MSL over nearshore waters slowly decrease in
coverage over the next few hours. Clouds with similar bases return
to coastal waters overnight with areas of BKN CIGs over coastal SD
County after 09z Thursday. 60-70% chance at KSAN and 40-50% chance
at KCRQ. Scattering to the coast again by 16z.

Valleys/Mountains/Deserts...VFR conditions with FEW-SCT thin high
clouds AOA 20 kft through Thu.

&&

.MARINE...
Northwest wind gusts around 20 kts near San Clemente Island this
afternoon and evening, diminishing after 06z. Otherwise, no
hazardous marine weather is expected through Sunday.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 8 PM PDT Thursday for Riverside County
     Mountains-San Bernardino and Riverside County Valleys-The
     Inland Empire-San Diego County Mountains-San Diego County
     Valleys.

     Extreme Heat Warning until 8 PM PDT Thursday for Coachella
     Valley-San Diego County Deserts-San Gorgonio Pass near
     Banning.

PZ...None.

&&

$$

PUBLIC...CO
AVIATION/MARINE...KW