textproduct: San Joaquin Valley

KEY MESSAGES

1. Dense fog and low clouds for the Central Valley tonight.

2. High confidence for rain and very high elevation snow (9000 ft) moving into Kern County early Wednesday, then spreading across the entire region New Year's Eve into New Year's Day.

3. Areas which received the heaviest rainfall last week, are most vulnerable to flooding. 70%-80% probability for 0.5 of rain at higher elevations, 30%-40% probability for 0.5 of rain in the valley, later Wednesday ending Thursday.

4. Lower confidence for a storm arriving Friday night into Saturday morning. Some alternate scenarios keep rain and snow across only Merced and Mariposa counties or miss the region entirely.

DISCUSSION

Patchy dense fog will continue in the San Joaquin Valley at times this evening. At this time, the lowest visibility is around Merced, or at 1/4 mile. However, dense fog becomes more widespread in the Central Valley later tonight. The fog may be a bit slower to clear than yesterday, but short-term ensemble guidance suggest it will lift by Noon Tuesday. Some high clouds arrive by late Tuesday afternoon and will herald the arrival of the next storm system.

Models continue to show a trajectory of subtropical moisture from the south that arrive arrive in Kern County by Wednesday morning. The probability of 0.01 inch of precipitation in Kern County is at least 50-60 percent by early Wednesday morning, though with a higher likelihood towards western Kern County. Chances for measurable precipitation begin later Wednesday morning across the forecast area. Snow levels begin very high on Wednesday, or about 9,000 to 10,000 feet, then lower to around 8,000 feet by New Year's Day. Several inches of snow are forecast to accumulate in the highest elevations. There is a high probability (70-80%) that many locations in the mountains from Yosemite NP to the Frazier Park area will see at least 0.50 inch by New Year's Day. Otherwise, lighter amounts are more likely to occur on the valley floor, but there is a 30-40 percent chance of a half inch. However, there is a 40-50 percent chance that the Kern County desert will see at least 0.50 inch, and this could lead to localized flooding.

Chances for precipitation linger into Friday, and another storm system arrives Friday night into the weekend. Lesser precipitation amounts are projected, but this will be a colder system. Although, the probability of 0.50 inch of rain in the mountain areas is about 40-50 percent from late Friday until late Saturday. As of now, snow levels are forecast to lower to around 7,000 feet on Friday and lower even more, or to 6,000 feet, by late Saturday. There is moderate confidence that another several inches of snow will accumulate at elevations mainly above 7,000 feet. Otherwise, lingering light showers continue Sunday into next Monday.

The Climate Prediction Center continues to favor above average precipitation for next week into the following week along with above average temperatures for much of the Golden State.

AVIATION

Expect intermittent patchy dense fog (LIFR to VLIFR conditions) in the San Joaquin Valley through 10Z Tuesday, then high confidence of widespread LIFR to VLIFR conditions from 10Z-20Z Tuesday. Otherwise, VFR conditions prevail for the next 24 hours.

AIR QUALITY ISSUES

On Tuesday December 30 2025, Fireplace/Wood Stove Burning Status is: No Burning Unless Registered in Fresno, Kern, and Madera Counties. Burning Discouraged in Kings, 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 from 2 AM to noon PST Tuesday for CAZ301>303-305>307-309>312-314>316.