textproduct: San Joaquin Valley

KEY MESSAGES

1. Dense Fog Advisory in effect from 12 AM tonight through 10 AM Thursday.

2. Confidence increasing for medium-to-high-impact valley fog event until this weekend.

3. Warm and pleasant weather throughout the area this week.

4. Precipitation returns to the northern Sierra Nevada Sunday into early next week with snow levels at 7,000 to 8,000 feet.

DISCUSSION

Temperatures are steadily lowering this evening and approaching closer to the dewpoints in the San Joaquin Valley. Dense fog develops later tonight and prevails for about two or three hours on each side of sunrise. Fog has a good chance to redevelop tomorrow night into Friday, as latest ensemble guidance suggests a probability of 45-55 percent for one quarter mile or lower visibility. The upper-level ridge persists and will keep the chances for dense valley fog into Saturday morning. Otherwise, above average temperatures continue with high probabilities of maximum temperatures above 75 degrees in the warmest locations, including the valley, along with high confidence of maxima exceeding 80 degrees in the Kern County desert.

Beginning late Saturday night/early Sunday morning, the next chance of precipitation returns the northern portion of our Sierra Nevada. Light amounts are projected at this time, and there is a slight chance for thunderstorms. Otherwise, temperatures gradually lower and eventually return to near seasonal values. The unsettled pattern will continue into Monday, and chances for showers/thunderstorms spread southward over the Sierra Nevada towards Sequoia NP. A few lingering showers will persist into Tuesday morning before a dry pattern returns. Snow levels will initially be 9,000 feet starting Saturday night, but will lower to 8,000 feet for Sunday and 7,000 feet by Monday. Cooling will occur, though temperatures will return to seasonal values by the middle of next week.

Latest CPC outlooks show a tilt in the odds towards above average temperatures and below average precipitation for both the 6-10 day and 8-14 day periods.

AVIATION

VFR conditions in the San Joaquin Valley through 10Z Thu gradually decreasing to VLIFR by 13Z with visibility reduced to one quarter mile and ceilings below 200 ft until 18Z when VFR conditions steadily return by 21Z Thu.

VFR conditions expected to persist in the Mojave Desert and Sierra Nevada.

AIR QUALITY ISSUES

On Thursday February 26, 2026, Fireplace/Wood Stove Burning Status is: No Burning Unless Registered in Fresno, Kern, and Kings Counties. Burning Discouraged in Madera, Merced, and Tulare Counties, and Kern (Greater Frazier Park Area) and Sequoia National Park and Forest.

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

Dense Fog Advisory until 10 AM PST Thursday for CAZ302-303- 305>307-310>312-315.