textproduct: San Joaquin Valley

KEY MESSAGES

1. Fog and low clouds will continue each night and morning across the San Joaquin Valley this week. Dense fog expected across the lower Sierra foothills, coastal ranges, and the Grapevine.

2. A gradual warming trend will occur across the mountains and desert this week, as the high pressure pattern continues over the region.

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

DISCUSSION

Building ridge pattern over the West Coast by the end of the week to re-enforce the current stagnant weather conditions. Therefore, will expect minor changes to the low clouds over the San Joaquin Valley and slight warming for locations above the clouds. As noted on previous days, slow warming trend expected outside of the San Joaquin Valley. Probability of seasonal normal values across the valley are still struggling with low percentage. On the contrary, outside of the San Joaquin Valley, the probability of reaching 65 to 70 degrees has been consistently reaching percentages of 60 and 80 percent. Therefore, confidence is high that at least the area outside of the San Joaquin Valley will see some changes this weekend.

Ensemble moisture analysis is not as confident with precipitation over Central California next week. Earliest onset of the arrival of precipitation is Monday night into early Tuesday morning. Yet, the mostly likely arrival time for measurable precipitation will be around late Tuesday afternoon. Ensemble longer range analysis does show the break-down of the ridge pattern with zonal flow extending into Northern California during the early to mid-week period. Yet, while Probability of Measurable Precipitation does not go above 50% during the period in question, light precipitation will occur from Merced County to Yosemite. Yosemite will also be at the higher end of the precipitation totals while Kern County will see the lowest values. As for snow, ensemble-mean snow-level will remain above 8,000 feet during the event. Keeping snow to near crest level. Lastly, ensemble cloud analysis does not show any good break-up of the low stratus during the next precipitation event. Therefore, gray skies may continue into the second half of December.

AVIATION

IFR ceilings and visibilities are expected to prevail for much of the San Joaquin Valley during the next 24 hours. LIFR conditions will also persist in the coastal ranges, Sierra foothills, and the Kern County mountains due to the low stratus deck. 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

On Thursday December 11 2025, Unhealthy for Sensitive Groups in Fresno, Kern, Madera, and Tulare Counties. Fireplace/Wood Stove Burning Status is: No Burning For All in Fresno and Kern Counties. No Burning Unless Registered in 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 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 11 AM PST this morning for CAZ300-304- 308-313-316>322-334>336.