Merced, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

849
FXUS66 KHNX 261801
AFDHNX

Area Forecast Discussion
National Weather Service Hanford CA
1101 AM PDT Wed Aug 26 2026


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.KEY MESSAGES...
1. Triple digit heat continues for the San Joaquin Valley this
week. Moderate to Major Heat Risk expected with a Heat Advisory
in effect through Wednesday evening, mainly Fresno County
southward.

2. Extreme Heat Warning in effect for the Mojave Desert through
Wednesday evening with Major Heat Risk expected. An 0 to 70
percent probability of temperatures of 105 degrees or hotter
with little overnight relief.

3. Moisture tracking over the region in the late week period
will bring a 10 to 15 percent chance for thunderstorms to the
Sierra Nevada crest.

4. Air Quality Alert for Merced County through Thursday morning
due to smoke from a local fire.

&&

.DISCUSSION...
Today is the last day of the Heat Advisory and the Extreme Heat
Warning. It is still forecasted to be quite hot in the Valley
and the Deserts. The Probability of Exceedance (PoE) of 100
degrees is 80-100% today for the SJV and a PoE of 104 degrees is
10-25%, mainly for Merced and Fresno counties. The lower half of
the SJV (south of Fresno county) will not exceed 104. The south
SJV has a PoE of 102 of 10-20%. So, the Fresno and Merced areas
will be between 100-104 degrees today and the rest of the valley
will be between 100-102. The Mojave desert will be much hotter
as they have an Extreme Heat Warning. The Mojave Desert
(specifically Ridgecrest) PoE of 106 is 70%, but drops to 42%
for temperatures exceeding 107 degrees. This drops to a 14%
chance when looking at PoE for 108 degrees.

A pattern shift is in the forecast still. The trough off the
Pacific Northwest coast is beginning to move on shore, but the
Central Valley will not feel its affects until Thursday and more
so on Friday. Moisture will be present, thanks to Tropical Storm
Iselle being sucked into the flow. There is a 5-10% chance of
thunderstorms in the Sierra Nevada crest on Thursday, which
increases to 10-20% chance on Friday. Also on Friday, there is
currently a 30-65% probability of 0.25" of rain or more in the
Sierra Nevada crest. In Fresno and Merced counties, we are
looking at a 5-10% chance of 0.10" or more of rain. These
chances go down further south, with Bakersfield currently having
a 0% chance of 0.10" of rain.

Heading into the weekend and next week, a second trough is
looking to come through. This`ll aid in temperatures staying
low, which is in line with the CPC`s 6-10 day outlook of 33-40%
chance of below normal temperatures. The CPC is also looking at
33-40% chance above normal precipitation for the same time
frame.


&&


.AVIATION...
VFR conditions prevailing for the next 24 hours. Over Merced
county, expect hazy and smokey conditions due to a fire north of
the city.

&&

.AIR QUALITY ISSUES...
The Valley Air District has issued an Air Quality Alert for
Merced County from Tuesday morning through Thursday morning due
to smoke from a local fire. Exposure to particle pollution can
cause serious health problems: aggravate lung disease, cause
asthma attacks and acute bronchitis and increase risk of
respiratory infections. In people with heart disease, short-term
exposure to particle pollution has been linked to heart attacks
and arrhythmias according to the US Environmental Protection
Agency. Children and elderly people are also more susceptible to
consequences of high particulate levels.
Stay indoors if possible. Avoid prolonged or strenuous outdoor
physical activities to reduce the affect of unhealthy air. For
current air quality go to fire.airnow.gov


&&

.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 Warning until 11 PM PDT this evening for
CAZ337>339.
Heat Advisory until 11 PM PDT this evening for CAZ304>316.
&&

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