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 will also develop at times in the lower Sierra foothills, coastal ranges, and the Grapevine.

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

DISCUSSION

As the ridge of high pressure maintains its grip across the Southwest, a stagnant weather pattern will exist over the region and keep Central California dry. Low clouds continue to plague the San Joaquin Valley as afternoon highs fall short of their seasonal normal values. Probabilities of reaching seasonal normal values struggle to reach a percentage higher than 10 percent for much of the week. On the contrary, outside of the San Joaquin Valley, the probability of reaching 60 degrees sits in between 70 and 95 percent. With these high percentage value showing up for much of the week, a warming trend is in store for the region. However, just not for the San Joaquin Valley.

In the realm of precipitation, ensemble moisture analysis is showing the blocking high maintaining its position over the Eastern Pacific, and placing the steering current in the direction of the Pacific Northwest. With little change in the next 5 day, Central California will remain dry and covered in low clouds. Longer range ensemble analysis does show a change in the pattern with a hint toward the introduction of precipitation as early as next Monday (15 Dec 2025). If the pattern toward precipitation holds, will investigate the extend of the next storm that could reach Central California.

AVIATION

IFR to MVFR 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 Mountains and Desert over the next 24 hours.

AIR QUALITY ISSUES

On Monday December 8 2025, Unhealthy for Sensitive Groups in Fresno, Kern, Madera, and Tulare Counties. Fireplace/Wood Stove Burning Status is: No Burning For All in Fresno, Kern, and Madera Counties. No Burning Unless Registered in Kings, 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.