textproduct: San Joaquin Valley

KEY MESSAGES

1. Dense Fog in the valley is expected for the next several days.

2. Slight chance of snow above 7,000 feet in the Sierra Nevada Thursday and Friday. Otherwise, dry conditions will prevail for the week.

DISCUSSION

Fog is generally a little slower to develop this evening as low stratus remained this afternoon after the fog had lifted. However, widespread dense fog is projected to return later tonight and last until at least late morning on Wednesday. There is a possibility that some locations may not get quite as foggy as during the last several days, as some mid and high clouds also passed over the fog/stratus today. These higher clouds may have aided in keeping the stratus intact over most of the valley through this afternoon. Currently, there have been reports of dense fog, per the ASOS at NAS Lemoore and webcams towards Buttonwillow. Outside of the Central Valley, warmer temperatures will prevail over the low cloud deck. More fog develops in the Central Valley again Wednesday night, but chances of widespread dense fog decrease a bit. Thus, will opt to keep the Dense Fog Advisory through Noon PST Wednesday at this time.

A weak upper-level trough will bring a slight chance for high elevation snow in the Sierra Nevada on Thursday, mainly above 7,000 feet with a slight chance of rain into the foothills, and as far south as Kern County. This system may temporarily halt fog formation, but this will likely be short-lived, as valley fog is projected to redevelop by Thursday night along with the return of upper-level high pressure ridging that will continue into early next week.

Latest CPC outlooks show a 60-70 percent chance of above average temperatures with a 40-50 percent chance of below average precipitation at the 6-10 day range. The 8-14 day range shows a 70-80 percent chance of continued above average temperatures, but with near average precipitation.

AVIATION

Visibilities across the TAF sites as of this update are mainly 3-5 miles; however, CIGs continue to be down to IFR and LIFR thresholds. Widespread IFR to LIFR conditions begin to prevail after 08Z Wednesday until at least 18Z. Winds remain light and variable through the TAF cycle. VFR conditions prevail for the Sierra Nevada, Coastal Range, and in the Mojave Desert for the next 24 hours.

AIR QUALITY ISSUES

On Wednesday January 21 2026, 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 until noon PST Wednesday for CAZ301>307- 309>312-314>317-319-321.