Grossmont, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

498
FXUS66 KSGX 290712
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
1212 AM PDT Mon Jun 29 2026

.SYNOPSIS...
High temperatures as much as 15 to 10 degrees below average for
the mountains and Inland Empire on Sunday will gradually warm for
the next week, but remain below average through the July 4th
holiday weekend. The marine layer will deepen tonight with patchy
drizzle possible late tonight. The marine will then gradually
decrease in depth, but with night and morning coastal low clouds
still extending into the western valleys late each night for next
weekend.

&&

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

.SHORT TERM (Today through Wednesday)...
Sunday was the coolest day in this current cooler pattern. Anaheim
and San Jacinto both set new records for the date for the coolest
high temperature while Ramona tied the existing record.

A low pressure system moving into northern California early today
will move through southern California tonight with low pressure
then beginning to weaken across the area for much of the week.

High temperatures for today will warm slightly at the coast and
around 5 degrees for inland areas with not much change on
Tuesday. High temperatures on Wednesday will warm a few degrees to
around 5 degrees in the mountains.

High temperatures on Sunday were as much as 15 to 20 degrees below
average for the mountains and Inland Empire. Even with the
warming for today through Wednesday, it will still be around 5
degrees below average near the coast and in the lower deserts on
Wednesday with the mountains and Inland Empire still 10 to 15
degrees below average.

That low pressure system from the north moving through the area
tonight will deepen the marine layer with patchy drizzle possible
late tonight. Southwest to west winds for the mountains and
deserts during the afternoon and evening will slowly decrease
this week.


&&

.LONG TERM (Thursday through Sunday)...
The trough of low pressure across the area will gradually weaken
on Thursday and Friday. For Saturday and Sunday, high pressure to
the south may begin to expand northward into southern California.
High temperatures as much as 5 to 10 degrees below average for
the mountains and inland valleys on Thursday will gradually warm
through Sunday, but remain below average.

High temperatures on Thursday will range from around 70 near the
coast to the 80s for the Inland Empire with 100 to 104 for the
lower deserts. On Sunday, high temperatures will range from the
lower 70s near the coast to the mid 80s to lower 90s for the
Inland Empire with 104 to 108 for the lower deserts.

&&

.AVIATION...
290530Z....Coast/Valleys/Foothills...Low clouds based 2000-3000 ft
MSL are developing into the inland valleys and into Orange County.
Slow expansion of clouds to continue through 10z, covering most of
the coastal basin. Small chance (10%) for -DZ/BR along coastal
slopes. Vis 0-5SM along foothill terrain. Clouds scatter out 15-18Z
Mon.

Patchy low clouds at the coast become BKN-OVC beginning around 00-
02Z Tue, then expand into inland areas. While the main cloud base is
expected to be around 2500-3500 ft MSL, there may be FEW-BKN cloud
layers down to 1500 ft MSL, as well as patchy -DZ/BR.

.Mountains/Deserts...West winds gusting 25-45 kt on the desert
slopes with local gusts to 55 kt through the San Gorgonio pass
diminish overnight into early Mon. MOD up/downdrafts in lee of
mountains and pockets of BLDU. Winds re-strengthen Monday after 22Z,
with similar gusts as this evening.

&&

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

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory until 2 AM PDT Monday for San Gorgonio Pass near
     Banning.

PZ...None.

&&

$$

PUBLIC...17
AVIATION/MARINE...Westerink