textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1205 AM PST Sat Jan 17 2026

- Dry weather, cool mornings, and warm afternoons continue

- Morning fog across the delta and interior valleys

UPDATE

Issued at 837 AM PST Sat Jan 17 2026

Once again, the interior East Bay Valleys and West Delta are experiencing areas of dense fog. Currently, both Byron and Concord airports are reporting less than 1/4 mile visibility. Patchy fog also prevails in the North Bay Valleys with high cloud cover working in from the south. As surface temperatures warm, the fog is expected to gradually mix out; first across the North Bay and by midmorning or early afternoon across the West Delta and interior East Bay Valleys. We will continue to watch closely how these high clouds will affect afternoon temperatures, but largely should still be another warm day across much of the region this afternoon with high temperatures in the mid 60s to mid 70s (up to 80 degrees F in the higher terrain). Otherwise, no updates are anticipated this morning as the forecast remains on track.

SHORT TERM

Issued at 1205 AM PST Sat Jan 17 2026 (Today and tonight)

Conditions are similar to last night, with a few subtle changes. First, the marine stratus has peeled off the coast. This is thanks to robust offshore flow. The SFO-WMC gradient is -12.3 mb, quite a bit stronger than most models have it analyzed. Mt. St. Helena is reporting ENE winds gusting as high as 47 mph tonight. This and several other mountain stations would actually be in Red Flag Criteria if the annual grasses were cured. This offshore gradient will weaken over the next 36 hours as both the strong surface high over the Rockies and the trough over California weaken. The other difference tonight is high clouds moving in from the south. These will help moderate both the min and max temperature by a degree or two and bring some color to the sunrise and sunset today. Otherwise it will feel very similar to yesterday.

LONG TERM

Issued at 1205 AM PST Sat Jan 17 2026 (Sunday through Friday)

Sunday will be a rinse and repeat of Saturday. Expect a chilly morning, warm afternoon and some high clouds through the day. This pattern will stick around as the strong ridging that extends all the way to the jet stream will continue through the week. There is a chance for a short wave trough at 500 mb to bring some very light rain Thu-Fri, but it's looking more and more like that will just be a cloud maker. That little trough is important though. It's the first domino to fall in the gradual pattern change. The 500 mb flow will likely become more zonal by next weekend. There's significant disagreement in the ensemble clusters after next weekend, but some solutions bring a legitimate troughing pattern and possible wet weather back for the last week of January. The 00Z ECMWF ensemble IQR has between 1.0-2.5" of rain from the 27th to the 31st at SFO.

AVIATION

(18Z TAFS) Issued at 902 AM PST Sat Jan 17 2026

Stratus is clearing out across the interior East Bay valleys as the Tule Fog starts to mix out across the Central Valley. The far interior could remain socked in through the day but CCR should clear out later this morning and afternoon. Generally VFR conditions with high level clouds prevail through the day elsewhere, with predominantly gentle winds and a largely offshore flow across the interior, with a gentle onshore breeze for the coastal areas. Overnight, radiational fog develops across the North Bay valleys, including STS and APC, and the East Bay valleys, although confidence is low for impacts at LVK, CCR has a better chance for reduced visibilities and lowered ceilings overnight. High resolution models are also placing some possibility for fog or low stratus at SJC later tonight, but this is a low confidence forecast at this time.

Vicinity of SFO... VFR through the TAF period. A gentle offshore flow develops in the afternoon and evening hours. Otherwise, winds remain light and variable.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... VFR through the TAF period. Light and variable winds through the daytime, with breezy valley drainage winds developing overnight.

MARINE

(Today through Thursday) Issued at 837 AM PST Sat Jan 17 2026

Moderate to breezy northeast winds continue across the San Pablo Bay, the delta, and through the Golden Gate through the weekend while light northeast to north winds persist across the rest of the coastal waters. Light seas continue into early next week before the next round of long period swell arrives and brings light to moderate seas in the mid week.

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...None.