Rancho Santa Margarita, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

927
FXUS66 KSGX 061645
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
845 AM PST Sat Dec 6 2025

.SYNOPSIS...
Warmer this weekend with the potential for patchy dense fog near
the coast tonight and again Sunday night. Much warmer next week
with highs 10-15 degrees above normal and periods of weak to
locally moderate Santa Ana winds, strongest on Tuesday.

&&

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

.Morning Update...

Satellite is showing cloud free skies across Southern
California. Temperatures this morning are starting out
in the lower 40s in the wind sheltered valleys and locally
in drainage basins. Coastal areas and foothills above the
inversion are experiencing a milder start in the 50s.
Temperatures remain on pace to reach into the lower 70s for
much of the coastal basin for a few hours this afternoon.
Coastal fog development tonight remains uncertain and patchy
at best. No changes currently to the forecast.


Previous discussion (2:20 AM Saturday)...

Skies remain clear this morning with light winds across the
region. Pressure gradients will be nearly neutral to the local
deserts through Sunday morning, allowing for a weak sea breeze to
develop this afternoon. With the return of this weak onshore
flow and a forecasted weak coastal eddy tonight, we could see a
development of dense fog over the coastal waters and locally into
the coastal areas tonight into Sunday morning. Weak offshore flow
kicks back in on Sunday morning, helping to clear out any fog.
Patchy dense fog may briefly return again Sunday evening before
slightly stronger offshore flow develops Sunday night. Aside from
that, there will be gradual warming through the weekend as an
upper level ridge of high pressure begins to build in from the
west. High temperatures today will be around 3-7 degrees above
normal, increasing to around 5-10 degrees above normal for Sunday.

Next week can be summed up with warm and dry. The upper high
slowly shifts east through the week, directly overhead by Friday.
At the surface, mostly weak Santa Ana winds will prevail, becoming
locally moderate on Tuesday morning as surface gradients peak.
With no upper level support, winds will remain confined to the
usual passes, canyons, and coastal slopes and follow a diurnal
pattern, strongest in the mornings and then weakening during the
afternoon. On Tuesday morning, northeast to east gusts in the
wind prone locations will generally peak around 30-45 mph. Monday
and Wednesday through Friday will see peak gusts closer to 20-35
mph. Only minor daily fluctuations in temperatures is expected,
with highs generally 10-15 degrees above normal each day Monday
through Saturday. Dry air and weak winds overnight will allow for
decent cooling, so HeatRisk remains low. For the valleys and
deserts it will very much be a winter in the morning, summer
(highs in the low 80s) for a few hours in the early afternoon,
and fall in the evening sort of pattern.

The forecast becomes a little more uncertain towards next weekend
with the upper high potentially beginning to weaken or break down,
influencing how much cooling we`ll see and whether or not onshore
flow will return. Still no signs of precipitation around here
until the second half of the month.


&&

.AVIATION...
061630Z....Low clouds/fog have the potential to develop along the
immediate coast after 03Z Sun. Chances are 10-20% in San Diego
County through 12Z Sun and 30-40% in Orange County through 19Z.
Areal coverage of any low clouds/fog will be patchy with bases less
than 500 ft and visibility 1 mile or less. Confidence is not high
enough in VIS restrictions to include fog in the TAFs at coastal
sites at this time. VFR conditions will prevail for inland areas
through the TAF period.

&&

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

&&

.BEACHES...
Morning high tide is predicted to be 6.5 to 7 ft on Sunday at 10 AM
in La Jolla and at 9:50 AM in Newport Beach. Astronomically high
tides may result in tidal overflow in normally dry beach areas. High
tide is predicted to fall below 6 ft by 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...Westerink
AVIATION/MARINE/BEACHES...CO