Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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796
FXUS66 KHNX 192310
AFDHNX

Area Forecast Discussion
National Weather Service Hanford CA
410 PM PDT Tue Aug 19 2025

.UPDATE...
Updated Aviation Section.

&&

.KEY MESSAGES...
1. A significant warming trend returns by the middle of the
week with triple digit heat in the warmest locations. The
potential for Major Heat Risk returns by Thursday in the Kern
County desert and enters into the Central Valley by Friday. An
Extreme Heat Watch has been issued for these areas.

2. There is a 10 to 30 percent chance for thunderstorms this
weekend with an influx of monsoonal moisture, with the greatest
chances along the Sierra crest.

3. Elevated fire risk with minimum relative humidity expected
to be less than 10 percent in the Mojave Desert and Kern County
mountains with breezy winds in the afternoon to evening. A Fire
Weather Watch for low humidity and locally breezy winds has been
issued for the Ft Tejon area from Wednesday until Saturday.

&&

.DISCUSSION...
A strong warming trend is expected over central California
towards the end of this week as an area of high pressure
gradually builds in over the region. Near-average highs today
and Wednesday will give way to triple-digit temperatures
approaching ten degrees above season averages, with some areas
nearing record highs during the weekend. Much of the San Joaquin
Valley has a 50 to 80 percent probability to exceed 105 degrees
Friday, and a 20 to 70 percent chance on Saturday, with the
greatest of these in the southern valley and urban areas. For
the urban and foothill areas, minimum temperatures will also be
well above normals, with a 30 to 90 percent chance to exceed 75
degrees Friday through Sunday. As a result, an Extreme Heat
Watch has been issued valid from 11 AM PDT Friday through 8 AM
PDT Sunday.

An Extreme Heat Watch has also been issued for the Mojave Desert
valid 11 AM PDT Thursday through 8 AM PDT Sunday due to
prolonged heat. There is a 40 to 95 percent probability to
exceed 105 degrees Friday and Saturday, with a 45 to 80 percent
chance on Sunday. There is a 20 to 60 percent probability to
exceed 75 degrees in the open desert areas, including Edwards
and California City, but with a greater chance at 85 to 100
percent for Mojave, Ridgecrest, and Inyokern.

Monsoonal moisture associated with the aforementioned area of
high pressure is also expected to entrain over the region this
weekend. The mid-level moisture and warming temperatures across
the area will allow for thunderstorm development across the
Sierra Nevada, with the best chances being Saturday and Sunday
afternoons at 15 to 30 percent across the higher elevations of
Fresno and Tulare counties.


&&


.AVIATION...
00Z Update:

VFR conditions are expected in the San Joaquin Valley for the next
24 hours.

&&

.FIRE WEATHER...
Warming temperatures across the region will cause minimum
relative humidity to lower for much of the lower elevations of
the area (the influx of moisture in the mid levels will cause
RH to increase in the Sierra). Widespread minimums 15 to 20
percent are expected for the San Joaquin Valley and Kern County
mountains and less than 15 percent in the Kern Desert. Lowering
RHs paired with stronger southerly wind gusts near 25 mph in
Frazier Park and Fort Tejon has led to the issuance of a Fire
Weather Watch as these conditions can cause rapid fire spread if
development occurs.


&&

.AIR QUALITY ISSUES...
None.



&&

.CERTAINTY...

The level of certainty for days 1 and 2 is high.
The level of certainty for days 3 through 7 is medium.

Certainty levels include low...medium...and high. Please visit
www.weather.gov/hnx/certainty.html for additional information
and/or to provide feedback.

&&

.HNX WATCHES/WARNINGS/ADVISORIES...
Extreme Heat Watch from Thursday morning through Sunday
morning for CAZ337>339.
Extreme Heat Watch from Friday morning through Sunday morning
for CAZ300>316-332.
Fire Weather Watch from Wednesday morning through Saturday
evening for CAZ597.
&&

$$

public/aviation...McCoy
idss..............EW

weather.gov/hanford