Chino Hills, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

361
FXUS66 KSGX 040356
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
856 PM PDT Thu Jul 3 2025

.SYNOPSIS...
Minor warming through the holiday weekend with highs near normal
and night and morning low clouds continuing along the coastal
areas and western valleys. A ridge of high pressure will
strengthen over the region, leading to building confidence in a
heat wave across the area and the potential first push of monsoon
moisture by the middle of next week.

&&

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

Evening update...
Low clouds have begun to spread back into the coastal areas this
evening, but elsewhere skies remain clear aside from high level
smoke from a wildfire in San Luis Obispo County. No changes to
the forecast this evening. Two main caveats in the forecast remain
for the middle of next week. One: if low-level moisture makes it
into the lower deserts during the peak of the heat wave, high
temperatures could end up being several degrees lower than what is
currently forecast for those areas. Two: while there is growing
confidence that monsoon moisture will spread into the area,
whether or not we get any precipitation on it will depend on the
position of the upper level ridge axis and associated subsidence
inversion acting as a cap.

Previous discussion...
A weak troughing pattern is expected to linger across
the the region through the weekend as high pressure builds across
the northern Mexico. As the high builds and pressure heights
increase a lot, subtle warming by a 3-5 degrees will occur by
Friday, lasting through the holiday weekend. This will bring
temperatures closer to normal for early July. Low clouds will
continue to push ashore each night into the morning for coastal
and western valley regions.

Confidence continues to increase on a building heatwave by the
middle of next week as high pressure over Mexico, moves over our
area. Exact placement of this system is becoming better aligned,
where it indicates the system peaking over much of Southern
California. This leads to increased confidence of storm chances to
be limited below 10 percent, as a slight uptick in monsoonal
moisture works its way into SoCal by Tuesday and Wednesday. This
will lead to a bit more humidity with the hot weather, especially
for mountains and deserts. 850mb temperatures peak on Wednesday
and Thursday as a near ~ 600 dm high moves over the region. This
will trigger highs near 10 degrees above normal by the middle of
the week with high confidence in temperatures rising over 100
degrees across the high desert and Inland Empire. We will also be
keeping an eye on mountainous areas, where NBM shows moderate to
high chances of places like Julian and Anza seeing highs reach at
least 95 degrees. 80s and 90s can be expected for other mountain
areas and valleys closer to the coast. Those with heat
sensitivities or without proper cooling methods should continue to
monitor the forecast. Ensemble models show a subtle decrease in
the high`s intensity by the end of the week, which would lead to
continued hot temperatures but not as intense.

&&

.AVIATION...
040315Z....Coast/Valleys...Low clouds based 1000-1500 ft MSL will
push inland into the western valleys and far western and southern IE
overnight. There is a 40% chance for clouds to reach as far as KONT
13-15Z. Localized VIS reductions down to 3-5SM for valley higher
terrain. Clouds to clear to the beaches by 16-17z Fri, with
lingering clouds at some beaches into the afternoon. Low clouds with
slightly lower bases 800-1200 ft MSL will reform and push back
ashore after 03Z Sat.

Mountains/Deserts...Mostly clear with unrestricted VIS through
Friday.

&&

.MARINE...
No hazardous marine weather conditions are expected through Tuesday.

&&

.BEACHES...
Building southerly swell (190 degrees) of 3 feet at 15-17 seconds
will generate elevated surf of 3-5 ft with sets to 6 ft along
southerly facing beaches through Saturday. In addition, strong rip
and longshore currents expected at all beaches Friday and Saturday.
A Beach Hazards Statement is in effect and contains more
information. Swell and surf will begin to lower on Sunday.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through Saturday evening for Orange
     County Coastal Areas-San Diego County Coastal Areas.

PZ...None.

&&

$$

PUBLIC...SS/APR
AVIATION/MARINE/BEACHES...CSP