San Marcos, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

225
FXUS66 KSGX 161620
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
920 AM PDT Wed Apr 16 2025

.SYNOPSIS...
Cooler, cloudier, and windier conditions expected through Friday.
Periods of scattered light showers are expected tonight into
Thursday morning and Thursday night into Friday. Dry and warmer
conditions expected for the weekend into early next week.

&&

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

Visible satellite at 9 AM was showing low clouds covering the
entire coastal basin. The marine layer will stay deep through
Friday, with low clouds expected to fill in the coastal basin each
night. Cooler conditions are expected today and Thursday. Highs
today are expected to be 5 to 12 degrees below average for areas
west of the mountains with further cooling expected into Thursday.

A low pressure system from the west will weaken as it moves through
Southern California bringing a chance for showers for late tonight
into Thursday morning for the mountains westward. Overall, rain will
be light with rainfall rates 0.10 inches per hour or less. Highest
accumulations will be on the coastal mountain slopes. A second low
pressure system from the north will bring a chance of showers for
Thursday night and Friday. Recent guidance shows a slight inland
shift to the track of that system, resulting in slightly drier
forecast. Latest high resolution guidance is indicating rainfall
rates 0.10 inch or less as well. Through Friday evening, rainfall
and liquid-equivalent above the snow level could range from less
than 0.10 inch near the coast to 0.25 to 0.50 inch in the mountains,
locally up to 0.75 inches. The snow level will fall to around 6500
feet on Friday with an inch or two of snowfall possible above 7000
feet.

Over the mountains and into the deserts, the increased onshore
pressure gradient from the passing lows will produce periods of
gusty westerly winds through Friday night. Peak gusts 40 to 55 mph
with isolated gusts to 65 mph are expected, most likely through
passes. Strongest winds will occur Thursday, but winds will remain
elevated into Friday.

Dry weather is expected with warming conditions for Saturday and
Sunday, continuing into early next week for inland areas while the
coast and valleys may cool slightly for early next week. With the
warming, high temperatures on Sunday will range from the mid to
upper 60s near the coast to the mid 70s to lower 80s for the Inland
Empire with the lower deserts around 90. Overall, high temperatures
will mostly be within around 5 degrees of average for Saturday
through Tuesday.

&&

.AVIATION...
161600Z....Coasts/Valleys/Foothills...Low clouds fill the coastal
basin into the coastal mountain slopes. Bases vary between 3000-4500
feet MSL, with tops to 4500-5500 feet, bringing vis reductions in
hills where clouds intersect terrain. Patchy -DZ is possible through
17Z. Scatter out will be random/patchy and intermittent this
afternoon, but with cloud bases mostly above 3000 feet MSL. Low
clouds with similar bases/vis to fill the coastal basin after 02Z
tonight into Thursday, again with occasional lower cigs and vis in -
DZ.

Higher Mountains/Deserts...SCT high clouds today and tonight.
Westerly winds to gradually increase after 20Z, with strongest gusts
45-55 knots through pockets of mountain passes and into deserts.
Strong up/downdrafts and isolated LLWS in lee of mountains such as
vcnty KPSP.

&&

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

&&

.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...CO/17
AVIATION/MARINE...CSP/MM