Area Forecast Discussion

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National Weather Service - San Joaquin Valley / Hanford, CA
Issued: Monday, June 30 2025 - 5:03 PM PDT

KEY MESSAGES...

1. Steady triple digit high temperatures are expected through at least Thursday in the San Joaquin Valley and Kern County desert. A possible cooling trend is indicated in the latest model guidance by Friday and next weekend.

2. Dryness is expected to continue through the next week with steady minimum RH's in the 15 to 25 percent range in the Central Valley and in the single digits for the Kern County desert. Light winds will keep fire risk low.

DISCUSSION... A weak upper-level trough is currently off the coast and will push into the region by Tuesday. This will provide little change in temperatures, but a slight chance of mountain thunderstorms towards Yosemite. Meanwhile, high pressure remains in control over the Golden State. Triple digit heat persists for the next few days, and probabilities remain moderate to high (50-80%) for the Central Valley until Wednesday and even higher in the Kern County desert (80 to near 100 percent chance) until Thursday. Winds will increase along the Mojave Desert slopes on Tuesday and Wednesday due to the presence of the upper-level trough. Although, the chances of a gust of at least 45 mph are at around 30-50 percent chance for both Tuesday and Wednesday evenings.

A stronger upper-level trough arrives late Thursday and will provide a noticeable cooldown for Independence Day (Friday). Better chances (50-80 percent) for 45 mph gusts are shown for the Mojave Desert slopes on Thursday night. The chances of triple digits diminish across the region by Independence Day, except the desert floor in eastern Kern County remains at 20-50 percent. For the weekend and early next week, high pressure will gradually build back into the region, so more widespread triple digits possibly return (currently at a 10-20 percent chance for the SJ Valley) by early next week.

AVIATION... 00Z Update:

VFR conditions will prevail for the next 24 hours across the Central California Interior.

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.