Bostonia, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

093
FXUS66 KSGX 112055
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
155 PM PDT Mon Aug 11 2025

.SYNOPSIS...
Hot inland through Tuesday with high temperatures around 5-8
degrees above normal in the mountains and deserts. Gradual cooling
Wednesday through next weekend. Night and morning low clouds will
continue along the coastal areas and far western valleys,
spreading slightly further inland later in the week as the marine
layer deepens.

&&

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

Tonight through tomorrow night...

High pressure conditions continue to dominate the region. Most of
the monsoonal moisture will remained confined to the east, although
there is just enough that there could be a isolated shower and
possibly a thunderstorm over the mountains this afternoon through
early evening. If this does occur, it would mainly be over the
mountains of San Diego County. Low level clouds will begin to slowly
regather and surge back inland by later this evening, although the
extent might not be as far eastward. Looking at high res models,
such as the HRRR, they do pick up on the development of a coastal
eddy which becomes quite pronounced. With the development of this,
it should help to not only increase coverage with slight thickening
of the marine layer, and also help to mitigate the threat for patchy
fog out over the coastal waters. That being said, there could still
be some areas of patchy fog, although there was not enough
confidence of this occurring this evening to put it into the grids.
Temperatures will still be on the more mild side for the overnight
lows, and with little transition in the longwave pattern, and the
ridge remaining over the desert southwest with little difference of
elevated heights of around 592 dm at 500 mb, high temperatures
tomorrow will be quite similar to where they will be today, with
even more confinement of mid-level moisture to the east and
resulting in nearly a nil chance of afternoon convection for the
mountains and deserts for tomorrow.

Wednesday through next weekend...

Wednesday will begin the transition of a slight cooldown and
increase of afternoon westerly winds for the normal areas vulnerable
to strong and gusty diurnal winds, such as within the Coachella
Valley. This is due to the ridge weakening along with the region
become more influenced by a longwave trough upstream over the E Pac
waters, which will be slowly progressing towards the region. This
will allow temperatures to become up to 10 degrees below the
seasonal average for this time of year for some of the locations,
especially within the Inland Empire, by this weekend. Dry conditions
will also continue as the trough keeps drier southwesterly winds in
the mid-levels over the region and suppresses monsoonal moisture
further east of the CWA. During this period in the forecast. The
marine layer will also slightly lift and thicken, extending
further inland in the upcoming nights.

&&

.AVIATION...
111945Z...Coasts/Valleys...FEW-SCT low clouds with bases 1000-1500
ft MSL are lingering along some beaches. Low clouds will become more
widespread and move inland after 02Z Tue, moving locally into
western valleys overnight. Bases will be 700-1000 ft MSL, locally
down to 300-600 ft MSL, and vis down to 2-4 SM near higher coastal
terrain. Low clouds will scatter out 15-17Z Tue, some beaches may
only see partial clearing Tue afternoon.

Mountains/Deserts...Mostly clear and VFR conditions into Tue AM,
except for a few cumulus clouds at 10000 ft MSL over mountain peaks
through 01Z Tue.

&&

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

&&

.BEACHES...
Long period (16-17 second) southwesterly (200-220 degree) swell will
bring elevated surf and a high rip current risk through Friday. Surf
of 3 to 5 feet with local sets 6 to 7 feet.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 8 PM PDT this evening for Riverside County
     Mountains-San Bernardino County Mountains-San Bernardino
     and Riverside County Valleys-The Inland Empire-San Diego
     County Mountains.

     Extreme Heat Warning until 8 PM PDT Tuesday for Coachella Valley-
     San Diego County Deserts-San Gorgonio Pass near Banning.

PZ...None.

&&

$$

PUBLIC...Stewey
AVIATION/MARINE/BEACHES...CO