La Mesa, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

484
FXUS66 KSGX 202026
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
126 PM PDT Fri Jun 20 2025

.SYNOPSIS...
Gusty westerly winds over the mountains and into the deserts through
Saturday with cooler conditions and a more extensive marine layer
low cloud coverage. Weak offshore flow Sunday will bring
temperatures up a few degrees. Below average temperatures will
continue early in the week, with a gradual warming for the middle to
end of the week.

&&

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

For the weekend, an upper level low off the coast of British
Columbia will dig southeast into the Great Basin. This will bring 5
to 15 degree below average temperatures from the coast to the
deserts Saturday. In addition, gusty westerly winds can be expected
over the mountains and into the deserts this afternoon and evening
and again Saturday afternoon and evening. Winds will be strongest
through the San Gorgonio Pass where gusts 55 to 60 mph are possible,
otherwise gusts will be 40 to 50 mph.

Marine layer low clouds and areas of fog will be persistent into
next week, with varying depth. The marine layer is expected to
deepen slightly Saturday, although the amount of deepening will
depend on the position of a potential eddy. As the upper level low
digs into the Great Basin Sunday, the pressure gradient will briefly
turn offshore bringing an uptick in northeasterly winds Sunday
morning. Those offshore winds look to stay on the weaker side, but
have the potential to inhibit low clouds reaching portions of the
Inland Empire and near mountain foothills.

A secondary low will develop in the mean trough Sunday night into
Monday and digs towards Southern California before progressing
westward on Tuesday. This will maintain cooler weather with highs 5
to 10 degrees below normal through Tuesday and marine layer low
clouds spreading into the western valleys each night. For Wednesday
through the end of next week, the upper level troughing shifts north
resulting in a gradual warming and less extensive night and morning
low clouds. Current forecast for the end of the week follows NBM
with highs within a few degrees of normal.

&&

.AVIATION...
202030Z....Coast/Valleys...Intermittent cigs along immediate coast
before low clouds begin to march inland after 01Z. Bases will be
1600-2000 feet MSL with tops to 3200 feet should eventually fill the
coastal basin by 13Z Saturday. Vis 1-5SM far inland. Scatter out
Saturday 17-20Z.

.Mountains/Deserts...Clear skies and unrestricted VIS through
Saturday. Westerly winds with gusts 25-45 knots through mountain
passes and locally into deserts, likely producing pockets of
up/downdrafts in lee of mountains/mountain passes in addition to
isold BLDU in the desert with VIS 3-5SM at times. A slight decrease
Saturday morning.

&&

.MARINE...
Northwest wind gusts 20-25 knots near San Clemente Island this
afternoon and evening. Otherwise, no hazardous marine conditions are
expected through Wednesday.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory until 11 PM PDT Saturday for Apple and Lucerne
     Valleys.

     Wind Advisory from 5 PM this afternoon to 11 PM PDT Saturday for
     San Diego County Deserts.

     Wind Advisory until 11 PM PDT Saturday for San Gorgonio Pass
     near Banning.

PZ...None.

&&

$$

PUBLIC...CO
AVIATION/MARINE...MM