669
FXUS66 KSGX 101613
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
913 AM PDT Thu Jul 10 2025

.SYNOPSIS...
Very hot inland and cool at the coast today. Friday will cool a
little, with minor day to day changes through the middle of next
week. A deepening marine layer will bring more coastal clouds
extending farther inland during the nights and mornings.

&&

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

Low clouds and fog covered coastal areas of San Diego County this
morning, but the summer sun and the shallow cloud depth will allow
for sunny skies today (except for patchy low clouds at some
beaches). Temperatures today will show a great contrast from the
temperate coast to the scorching desert. Highs today at the coast
will be in the mid to upper 70s, while the low deserts flirt with
120 degrees and daily high temperature records. Extreme heat
warnings are in place for the lower deserts today, but this should
be the final day of extreme heat. In the valleys, highs will be
in the 90s to about 106 and a heat advisory is out today,
particularly for the more inland valleys where temps exceed 100.
These inland highs represent 6 to 12 degrees above normal today. A
temporary but strong ridge overhead has brought our region the
kind of subsidence and compressional heating needed for this heat
episode. This high will weaken slightly Friday, and some gulf
moisture creeps into the lower deserts, allowing for a drop of
several degrees, but still up to 8 degrees above normal in the low
desert for mid July. Valleys will trend close to normal for the
weekend. The marine layer will get a boost by a coastal eddy
tonight and Friday to rebuild and extend low clouds and fog into
western valleys and for a longer time each night and morning. For
next week, minor variations in the upper high will maintain this
rather seasonal weather, except slightly hotter than average in
the deserts.

&&

.AVIATION...
101615Z....Coast/Valleys...Low clouds have largely scattered out but
a few patches (based ~1000-1400ft MSL) remain locally along some
beaches. Expecting full clearing of the beaches and nearshore waters
by 17-18z with VFR prevailing throughout the day. Aided by a coastal
eddy tonight, low clouds return tonight with higher bases and more
inland extent. 70% chance for CIGs at KSAN by 07z with KCRQ likely
closer to 09z. Clouds may reach KSNA around 10-14z, but there is
about a 40-50% chance of this. Bases will be closer to 1000-1500ft
MSL with about 10-15 miles of inland extent.

Mountains/Deserts...VFR conditions and unrestricted VIS with FEW
thin high clouds AOA 20 kft through Fri.

&&

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

&&

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

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

PZ...None.

&&

$$

PUBLIC...MM
AVIATION/MARINE...Munyan