textproduct: San Joaquin Valley

UPDATE

Aviation and Air Quality Sections Updated

KEY MESSAGES

1. Fog, while dense at times, and low clouds will continue each night and morning across the San Joaquin Valley into the foothills up to 2,500 feet through early next week.

2. Above average temperatures will continue across the mountains and desert this week, as the high pressure pattern persists over the region.

3. Precipitation makes its return to Central California by the middle of next week after having a dry start to December.

DISCUSSION

The consistent stable pattern over the southwest will continue through at least the beginning of next week, with strong ridging keeping the low stratus clouds in place for the San Joaquin Valley and dense fog for the foothills of the Sierra Nevada and the Coastal Range from elevations of 1000 feet to 2500 feet. This stratus may also lower further down during the nighttime hours and lead to fog in the Valley itself.

There are indications of a pattern change beginning by next Tuesday night into Wednesday with some light precipitation possible in Central California as far south as Madera County, with current probabilities for a tenth of an inch of rainfall at 10 to 20 percent from Madera northwards. There are also 25 to 35 percent probabilities for an inch of snowfall in the Sierra Nevada, with snow levels from the NBM 25th percentile at 7500 feet and at the NBM 75th percentile closer to 95000 feet on Wednesday afternoon. These percentiles have closed by about 500 feet on either side, which shows an increase in confidence. This system may also be unsettled enough to push the current stratus out of the Valley, though any new rainfall may cause dense fog development in the Valley afterwards.

Looking into the long term, the Climate Prediction Center has outlined Central California for a slight risk for heavy precipitation from December 20th through December 26th, as well as the Sierra Nevada for heavy snow. The ECMWF 500mb model is also indicating a trough may move through around that time frame, meaning unsettled weather may return again to the region after the weak system coming in on Wednesday next week.

AVIATION

IFR to LIFR ceilings and visibilities are expected to prevail for much of the San Joaquin Valley during the next 24 hours, with a 45 to 60 percent chance of VLIFR due to fog until 19Z Saturday. LIFR conditions will also persist in the coastal ranges, Sierra foothills, and the Kern County mountains due to low clouds. Otherwise, VFR conditions will prevail in the Sierra Nevada and in the Kern County mountain and desert areas over the next 24 hours.

AIR QUALITY ISSUES

ISSUED: 12/13/2025 13:46 EXPIRES: 12/14/2025 23:59

On Sunday December 14 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 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

None.