Rancho Santa Margarita, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

240
FXUS66 KSGX 051009
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
309 AM PDT Thu Jun 5 2025

.SYNOPSIS...
There is a slight chance of showers and thunderstorms for this
afternoon for the San Bernardino Mountains and adjacent high
desert areas. A deep marine layer will continue into Friday
morning with patchy night and morning drizzle. The marine layer
will become shallower for the weekend into next week with night
and morning coastal low clouds not spreading as far into the
valleys. There will be a gradual warming trend through the
weekend, continuing into early next week for the mountains and
deserts, followed by a cooling trend for the middle of next week.

&&

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

.SHORT TERM (Today through Saturday)...
Moisture over the mountains and deserts will continue to decrease
today with a slight chance of afternoon showers and thunderstorms
for the San Bernardino County Mountains and adjacent high desert
areas.

The marine layer is around 3500 feet deep with the saturated cloud
layer below the base of the marine inversion around 2000 feet
deep. There has been patchy drizzle since Wednesday evening with
the light measurable amounts mostly for the coast and valleys of
San Diego County and in southern Orange County near the coastal
foothills of the Santa Ana Mountains. The marine layer will remain
around 3000 to 3500 feet deep into Friday morning with slow or
limited afternoon clearing for the San Diego County coast. The
marine layer will decrease to around 2000 to 2500 feet during the
weekend with night and morning coastal low clouds not spreading as
far into the valleys.

A slow warming trend will continue into the weekend, and continue
into early next week for the mountains and deserts. High
temperatures on Saturday will be around average near the coast to
a few to around 5 degrees above average for inland areas. High
temperatures on Saturday will range from around 70 near the coast
to the 80s and lower 90s for the Inland Empire with 103 to 107
for the lower deserts.

&&

.LONG TERM (Sunday through Wednesday)...
The gradual warming trend is expected to continue for the
mountains and deserts through Tuesday with high temperatures for
the mountains and deserts for Monday and Tuesday 5 to 10 degrees
above average.

There remains the spread in the guidance in whether a weak low
pressure system off the California coast will move into southern
California for early next week or instead weaken and move to the
west with high pressure to the south beginning to expand into
southern California.

The scenario with the weak low pressure system moving into
southern California would result in a deeper marine layer with
cooling for the coast and valleys. The scenario with high pressure
expanding northward into the area would be warmer with the marine
layer becoming shallower.

&&

.AVIATION...
050930Z....Coast/Valleys...Low clouds based 800-1800 feet MSL fill
the entire coastal basin with tops pushing into mountains up to 3500
feet. Vis 0-5SM over higher coastal and inland terrain and in -DZ.
Scatter out 16-18Z for inland areas, 18-21Z for Orange County, and
only partial if any clearing at all for San Diego County coastal
areas. Low clouds push inland again after 00Z with very similar
coverage, bases, vis, and patchy -DZ overnight into Friday.

Mountains/Deserts...Mostly clear today and tonight. Except for
cumulus and ISO SHRA/TSRA based at 10000 feet MSL 18-01Z over
mountains and high desert.

&&

.MARINE...
No hazardous marine conditions are expected today through Monday.

&&

.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...17
AVIATION/MARINE...MM