textproduct: San Joaquin Valley

KEY MESSAGES

1. Minor Heat Risk through the weekend as temperatures drop to seasonal normals.

2. Low pressure trough approaches California Sunday, bringing cooler weather and next chances for precipitation.

3. Moderate chance for above normal temperatures for early October.

DISCUSSION

Preliminary data indicates much of the San Joaquin Valley south of Merced County reached triple digits today, including the official climate sites at Bakersfield and Fresno. Whether this will be the last 100 degree day of 2026 remains to be seen. For now, a neutral atmospheric pattern is establishing over California, returning temperatures back to seasonally average Friday and Saturday. Heat Risk will be minor and only concern those extremely sensitive to heat or without cooling/hydration.

Looking ahead to next week, models continue to show a combined trough approaching California and tropical moisture push northward from Hurricane Polo and Odalys. There is still high uncertainty regarding a precipitation ranges, but the National Blend of Models (NBM) continues to show chances for rainfall across the Sierra Nevada starting Monday. A moderate chance (40-50%) for a trace or more rainfall is forecast Monday morning through Tuesday afternoon. A 20-30% chance for a trace of rain or more also extends into the Mojave Desert and slopes of Kern County on Tuesday. Slight chances (10-20%) for snowfall have entered the NBM forecast Monday morning above 9,000 feet elevation, but forecast confidence regarding even a dusting of snow is low at this time.

What is more certain is a region-wide cooldown with this trough. By Monday, expected high temperatures fall to the low 80s across the San Joaquin Valley and Mojave Desert with just a slight chance (10-20%) for high temperatures above 85 degrees. After the trough passes through California, temperatures are expected to return back to above average by the end of next week.

The probability for above normal temperatures at the start of October are continuing to trend upward. According to the 6-10 and 8-14 Day Outlooks from the Climate Prediction Center, there is a 50-60% chance for above normal temperatures through October 8. Near normal precipitation is forecast, with no strong signal to indicate how rainfall will trend to start the month.

AVIATION

VFR conditions will prevail 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.