FXUS66 KHNX 230547
AFDHNX

Area Forecast Discussion
National Weather Service Hanford CA
1047 PM PDT Sat Aug 22 2026


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.KEY MESSAGES...

1. Triple digit heat continues for San Joaquin Valley and Mojave
Desert. 40 to 50 percent for Major Heat Risk in the Southern San
Joaquin Valley early next week. 

2. 10 to 20 percent probability for extreme heat in the Mojave 
Desert ending next week and starting September.

&&

.DISCUSSION...

High pressure over the Four Corners region has resulted in upper
level flow over central California from the southwest, forcing
temperatures into the upper 90s to near 100 across the lower 
elevations of the region. With minimal change expected to the 
synoptic pattern, these temperatures are likely to stick around 
through much of the upcoming week. Through Wednesday, there is 
an 80 to 90 percent probability for afternoon highs to exceed 
100 degrees each day in the San Joaquin Valley. This level of 
heat will result in a Moderate Risk of heat-related illnesses to
those sensitive to heat, such as older adults (65+), infants, 
athletes, outdoor workers, those without effective cooling, and 
those with chronic diseases; there is some risk to the general 
population. Meanwhile, in the Mojave Desert, there is at least a
60 to 70 percent probability for afternoon highs to exceed 105
degrees this Tuesday and Wednesday, leading to patchy areas of
Major Heat Risk. 

A weak low pressure trough will push through the Pacific
Northwest region before the weekend, slightly degrading the
strength of the aforementioned high pressure. Upper level flow
will shift to the west from the southwest, resulting in slightly
cooler, but still above average, temperatures. However, the high
will maintain most of its strength over the desert areas, with
an additional 70 to 80 percent probability for highs to exceed
105 degrees. During the same period, there is a 50 to 60 percent
probability for morning lows to exceed 75 degrees. The
combination of these warmer highs and lows in the desert will
lead to more widespread Major Heat Risk with smaller areas of
Extreme Heat Risk developing. The latter of these has a 10 to 20
percent probability to occur.

As has been the case for much of the latter half of the summer,
the warmer temperatures will drive down the relative humidity
across the region. Through most of this coming week, minRH
values in the San Joaquin Valley will be between 15 and 25
percent and up to 30 percent in the Sierra Nevada; single 
digits will be present in the Mojave Desert. 

&&


.AVIATION...
VFR conditions prevailing for the next 24 hours.

&&

.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...
None.
&&

$$

public...McCoy
aviation....ND

weather.gov/hanford