textproduct: San Joaquin Valley

KEY MESSAGES

1. Heat Advisory remains in effect for the San Joaquin and Kern River Valley until 11 PM Tuesday.

2. Widespread Moderate Heat Risk, including triple-digit heat, in the lower elevations Thursday until next weekend. Some pockets of Major Heat Risk, particularly near urban areas.

3. Hot and dry conditions will create increased fire risk in eastern Kern and Tulare Counties this weekend.

4, 10-15% probability for thunderstorms in the Sierra Nevada the next few days, which may include dry lightning.

5. Practice safety around lakes, rivers, and streams, as water is still running cold.

DISCUSSION

Our area's introduction to summer 2026 remains today and through most of the work week. Atmospheric ridging continues to hold over California, with afternoon highs around 100 across the San Joaquin & Kern River Valleys and Mojave Desert. Latest model runs indicate Tuesday has the greatest probability (40-50%) for temperatures above 105 in the central San Joaquin Valley south of Fresno. With overnight lows only in the upper 60s to low 70s (particularly in urban areas), the accumulated heat exposure is significant. It is imperative to ensure access to proper cooling, stay hydrated, limit outdoor activity, and wear light and breathable clothing if you must be outdoors. Take extra precaution for vulnerable people and for animals and check in on those in need.

Cluster guidance continues to indicate strong agreement that ridging will break down to some degree starting Thursday, helping temperatures return closer to seasonal average. That being said, the prolonged period of hot and dry conditions has brought elevated fire risk, particularly in eastern Kern and Tulare Counties. All areas should exercise caution, however, as we have seen numerous fires across the entire area recently. This fire risk includes the 10-15% thunderstorm probability for the Sierra Nevada throughout the week bringing a risk of dry lightning.

As people attempt to cool down from these hot temperatures, please remember that waterways are still running cold. Even the most experienced swimmers can lose dexterity in 10-15 minutes in water that is 50 to 60 degrees.

AVIATION

VFR conditions expected in the San Joaquin Valley for the next 24 hours. Any thunderstorms that form over the Sierra Crest this afternoon may include strong winds, rain, small hail, lightning, and turbulence.

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

Heat Advisory until 11 PM PDT Tuesday for CAZ300>321-332.