textproduct: San Joaquin Valley

UPDATE

Updated Aviation Section.

KEY MESSAGES

1. Flood Watch from 10pm Wednesday to 10pm Thursday for for the southern and eastern Kern county.

2. High confidence for heavy rain Wednesday night through the morning of New Year's Day for Kern County, then spreading across the entire region later in the day.

3. Probability of 60%-70% for 1 of rain in 48 hours in the higher elevations and desert of Kern county. Areas which received the heaviest rainfall last week are most vulnerable to flooding.

4.Storm #2 arriving Friday night into Saturday morning, impacting the foothills of Mariposa, Madera and Fresno counties the most.

DISCUSSION

Band of high and mid-level clouds continues to pass over the forecast area at this time. The author has moderate confidence that these preclude fog development in the Central Valley, as latest HREF guidance shows a 30-40 percent chance for visibility below 1/2 mile. It is possible that visibility briefly drops then quickly rebounds at times overnight tonight. Otherwise, low stratus will linger tonight into Wednesday morning beneath the higher level clouds. Showers arrive by Wednesday afternoon, with a moderate chance of precipitation as early as the morning hours towards Kern County and nearby counties in our area.

Precipitation begins in earnest by the evening, and heavier amounts are projected after the clock strikes midnight for 2026. The probability for at least one inch of rain by the afternoon of New Year's Day is about 45-55 percent in the Sierra Nevada up to around 8,000 feet and near 60 percent for essentially all of the Kern County mountains. A Flood Watch will remain in effect for these areas, as well as the desert. Snow amounts will be mainly light, as there are moderate probabilities for amounts up to 6 inches above 8,000 feet.

The next system brings more impacts to our northern areas. Chances for an inch of precipitation for a 24 hour period ending Saturday afternoon rise to 70 to 80 percent for the Sierra Nevada, generally in Fresno County northward at elevations up to 7,000 feet. The chances for a foot of snow above 7,000 feet are at 50-60 percent in the Sierra Nevada. Snow levels lower to around 6,000 feet by Saturday afternoon, or after much of the precipitation ends. Unsettled conditions with snow levels steady around 6,000 feet will occur Sunday through early next week.

The CPC continues to favor above average precipitation and above average, or mild, temperatures for the Golden State out to 6-14 days ahead.

AVIATION

IFR/LIFR visibilities expected to continue at the TAF sites through 18Z Wednesday, becoming MVFR across the region with SHRA after 21Z Wednesday.

AIR QUALITY ISSUES

On Wednesday December 31 2025, Fireplace/Wood Stove Burning Status is: No Burning Unless Registered in Fresno, Kern, Kings, Madera, Merced, and Tulare Counties. Burning Discouraged in Kern (Greater Frazier Park Area) and Sequoia National Park and Forest.

CERTAINTY

The level of certainty for days 1 and 2 is medium. 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

Flood Watch from this evening through Thursday evening for CAZ333>339. Dense Fog Advisory until 11 AM PST Thursday for CAZ301>303- 305>307-310>312-315. Wind Advisory until 7 PM PST this evening for CAZ335.