Mesa Grande, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

282
FXUS66 KSGX 110409
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
909 PM PDT Sun Aug 10 2025

.SYNOPSIS...
Hot temperatures prevail for most locations through Wednesday
before a gradual cooling trend and a deepening marine layer helps
return temperatures to near normal by the end of the week and
below normal by the weekend.

&&

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

This afternoon saw a few thunderstorms develop over the Santa Rosa
Mountains in Riverside County, although no impacts from the storms were
reported. At this hour, areas of low clouds over the coastal
waters are being pushed offshore. The marine layer is marginally
deeper than yesterday and if the low clouds could move ashore,
they may spread farther inland than last night. High-resolution
models suggest that the low clouds and fog will push a little
farther inland by sunrise.

From previous discussion...
The main story remains the unseasonable temperatures. High
pressure slides down into Central California on Monday, spreading
into southeastern California Tuesday. With drier conditions and
the upper level ridging, high temperatures across the mountains
and deserts will remain hot through Tuesday, around 5-10 degrees
above normal, and heat products remain in effect. Luckily, with
the departure of the low and mid level moisture, the deserts and
mountains will be able to more effectively cool off during the
overnight hours, allowing for some relief from the heat. The
decreasing moisture will also all but eliminate the chances for
afternoon convection from Monday going forward. By Wednesday, the
ridge will begin to breakdown and shift into the Four Corners
region, with weak troughing setting in for the end of the week.
This will support a gradual cooldown through Friday, with each day
3-5 degrees cooler than the day before. With troughing returning,
the marine layer will deepen, spreading further inland each
morning. By the weekend, temperatures region- wide look to be 5-10
degrees below normal.

Further troughing into early next week looks possible as a
low moves down along the coast of Canada, but newer runs have
attempted to shift high pressure back over the Desert Southwest,
possibly returning the region to a warming trend. For now,
slightly below normal temperatures are expected to prevail into at
least early week.

&&

.AVIATION...
110345Z...Coasts/Valleys... Low clouds remain patchy and still over
the waters as 0330z Mon. Clouds should continue to gradually fill in
and bring CIGs to KSAN and KCRQ by 06-08z, with only a 60% chance
that clouds reach KSNA and fully through Orange County. The clouds
will have bases of 800-1200ft MSL with about 15 miles of inland
extent, primarily in San Diego County. Any clouds that push ashore
will quickly scatter out by 16-17z Monday.


Mountains/Deserts...VFR conditions continuing through Monday
evening. Iso Cu above 15,000 ft MSL over mountain peaks after 18z
Monday.

&&

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

&&

.BEACHES...
Long period (16-17 second) southwesterly (200-220 degree) swell will
bring elevated surf and high rip current risk Monday into the
upcoming weekend. Surf of 3 to 6 feet with the highest sets along
south and southwest facing beaches.

&&

.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 Monday for Riverside County
     Mountains-San Bernardino County Mountains-San Bernardino
     and Riverside County Valleys-The Inland Empire-San Diego
     County Mountains.

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

PZ...None.

&&

$$

PUBLIC...PG
AVIATION/MARINE/BEACHES...Munyan