Rancho Santa Margarita, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

343
FXUS66 KSGX 071130
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
430 AM PDT Wed Oct 7 2026

.SYNOPSIS...
The long-duration heatwave will continue for the coast and
valleys through Thursday and through Friday for the lower deserts.
Cooling will spread inland for Friday and Saturday, but high
temperatures will remain around 5 degrees above average on
Saturday. A low pressure system from the southwest on Sunday and
north on Monday and Tuesday combined with tropical moisture will
bring showers for late Saturday night through Sunday night with
continuing chances for showers through Tuesday night.

&&

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

...UPDATED AVIATION DISCUSSION...

.SHORT TERM (Today through Friday)...
The long-duration heatwave will continue for the coast and
valleys through Thursday and through Friday for the lower deserts.
Inland areas will warm a few degrees today while the coast into
the western San Diego County valleys cools a few degrees. There
will be Moderate HeatRisk for the beaches and far inland valleys
today with Major to locally Extreme HeatRisk for the rest of the
coast and valleys. There will also be areas of Major HeatRisk in
the lower deserts today.

Cooling at the beaches will begin to spread inland on Thursday with
Moderate to locally Major HeatRisk for the coast and valleys with
Major HeatRisk for the lower deserts. High temperatures on Friday
will cool a few to around 5 degrees with high temperatures around
10 degrees above average. High temperatures will range from the
upper 70s to mid 80s near the coast to the 90s for the Inland
Empire with 102 to 106 for the lower deserts.

There could be some patchy low clouds and dense fog near the
southern San Diego County coast early this morning with low clouds
and locally dense fog over the coastal waters spreading locally
inland along the coast for late tonight into Thursday morning with
a little farther inland spread of the low clouds into coastal
areas for late Thursday night into Friday morning as the marine
layer slowly deepens.

&&

.LONG TERM (Saturday through Tuesday)...
The cooling trend will continue through Tuesday with high
temperatures on Tuesday as much as 10 to 15 degrees below average
for the mountains, deserts, and inland valleys. High temperatures
for next Tuesday will be mostly in the 70s for the coast and
valleys with the lower deserts in the lower to mid 80s.

A closed low pressure system will develop off the California
coast on Thursday. This low pressure system will move toward the
southeast and absorb the moisture from former Hurricane Rachel,
then move northeastward into southern California and northern
Baja bringing showers for late Saturday night through Sunday with
another closed low pressure system from the north continuing
chances for showers for Monday and Tuesday.

NBM chances for 0.10 inch or more of rainfall through Sunday
night are 45 to 55 percent with chances for 0.50 inch or more
ranging from 30 percent near the coast to 40 percent for the
mountains. Chances for 1 inch or more of rainfall range from 15
percent near the coast to 25 to 35 percent for the mountains.

Through Tuesday night, NBM chances for 0.25 inch or more of
rainfall ranges from 50 percent near the coast to 55 to 65 percent
in the mountains. Chances for 1 inch or more of rainfall ranges
from around 25 percent near the coast to 35 to locally 45 percent
in the mountains. Chances for 2 inches or more of rainfall ranges
from around 5 percent near the coast to 10 to 15 percent for the
mountains. There could be a few inches of snowfall on the very
highest mountain peaks above 9000 feet for Monday night and
Tuesday as snow levels lower to 8000 to 8500 feet.

Onshore winds will strengthen for Sunday and Monday with southwest
to west winds for Sunday afternoon through Monday morning gusting
to 20 to 30 mph for the coastal waters to the valleys and to 35 to
45 mph for the mountains and deserts with gusts to 55 to 65 mph
for the northern Coachella Valley below the San Gorgonio Pass.

&&

.AVIATION...
071130Z...Coast: Isolated and intermittent patches of low clouds and
fog through 16Z. Any cigs would be around 500 feet MSL with vis 1-
5SM. Greater coverage of low clouds and fog more likely after 10Z
Thursday. Bases would be 400-600 feet MSL and vis 1-6SM.

Otherwise...clear skies except for cumulus based around 10 kft over
mountains 19-01Z.

&&

.MARINE...
No hazardous marine conditions are expected through Sunday.
Stronger westerly winds develop late Sunday.

&&

.BEACHES...
Increasing south swells will create surf of 3-5 feet with sets to 6
feet on south and southwest facing beaches through Friday, creating
hazardous swimming conditions for inexperienced swimmers. This
elevated surf will combine with high tides during the mornings and
evenings to generate local coastal flooding and beach erosion. The
Beach Hazards Statement and Coastal Flood Advisory contain the
details.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Extreme Heat Warning until 8 PM PDT Thursday for Orange County
     Coastal Areas-Orange County Inland Areas-San Bernardino and
     Riverside County Valleys-The Inland Empire-San Diego County
     Coastal Areas-San Diego County Valleys-Santa Ana Mountains
     and Foothills.

     Beach Hazards Statement through Friday evening for Orange County
     Coastal Areas-San Diego County Coastal Areas.

     Coastal Flood Advisory until 11 AM PDT Friday for Orange County
     Coastal Areas-San Diego County Coastal Areas.

     Extreme Heat Warning from 10 AM this morning to 8 PM PDT Friday
     for Coachella Valley-San Diego County Deserts-San Gorgonio
     Pass near Banning.

PZ...None.

&&

$$

PUBLIC...17
AVIATION/MARINE/BEACHES...MM