Issued at 844 AM PST Mon Jan 19 2026
Once again, patchy fog is being reported in the North Bay Valleys, particularly in Sonoma County and eastern portions of Marin County. However, visibilities are forecast to improve within the hour. Meanwhile, tule fog (dense at times) has pushed westward into the San Pablo/Suisun Bay, Delta, and interior East Bay Valleys this morning. This is mainly impacting places in and around Concord, Walnut Creek, Antioch, Brentwood, and Byron. Across this area, look for conditions to improve by late morning as surface temperatures begin to warm and allow for the fog to mix out. Otherwise, no updates anticipated at this time. For more information, see the previous forecast discussions below.
, Issued at 246 AM PST Mon Jan 19 2026 (Today and tonight)
Patchy fog is developing in the North Bay Valleys with intermittent reports of dense fog (1/4 statute mile visibility or lower) coming in from KSTS (Santa Rosa Airport) and KDVO (Novato/Gnoss Field Airport). Will hold off on a Dense Fog Advisory for now as the areas of dense fog are localized/not widespread on the webcam footage. If anyone is commuting in the North Bay Valleys, East Bay Valleys, or along the San Pablo/Suisun Bay and Delta areas this morning, be aware of the potential for dense fog, be prepared for sudden changes in visibility, and remember to slow down.
High pressure remains the name of the game. A ridiculously resilient ridge remains fixed over the West Coast with temperatures running anywhere from 5 to 15 degrees above normal for this time of year. High temperatures on Sunday were generally in the mid to upper 60s across the lower elevations of the Bay Area, upper 60s to low 70s across the higher elevations, and low to upper 70s across the Central Coast. The temperature distribution for today looks to be fairly similar with highs in the mid to upper 60s across the Bay Area and upper 60s to mid 70s throughout the Central Coast. Guidance shows a shallow (500 ft) marine layer developing tonight which may bring additional fog and low clouds to portions of the coastline tonight. Winds remain light and offshore through midweek.
..issued at 246 AM PST Mon Jan 19 2026 (Tuesday through Sunday)
Ridging sticks around through at least midweek before an upper level trough pushes in late Wednesday into Friday. This upper level trough will develop as a cut-off low and move southwards along the California coastline late this week. Unfortunately, this system looks to be dry with no rain expected from this system. PWAT values are between 0.7"-0.8" with a slightly stronger moisture tap entering southern California (where models show the potential for light rain). In the wake of this cut-off low, upper level ridging redevelops over the West Coast this weekend into next week. Rain lovers should not fully despair yet as models do signal some potential for rain to return late January/early February. The ECMWF shows some potential for light rain in early February with deep upper level troughing pushing into the West Coast. Models have consistently showed something developing late January/early February but the timing continues to be pushed back. The timing of the return of rain will become more clear as we get closer in time to late January/early February.
While we aren't expecting any rain with this upper level trough, it will bring in cooler air amd a return of more seasonal temperatures. High temperatures remain warm on Tuesday with highs in the mid 60s to low 70s (approximately 5 to 10 degrees above normal). Temperatures cool into the upper 50s to mid 60s Wednesday into the weekend as the ridge breaks down and cooler air arrives with the upper level trough. As the ridge rebuilds over the weekend, temperatures may warm by a few degrees but overall remain seasonal in the low to mid 60s. Winds shift onshore mid to late week as the upper level low moves down the coastline but they will shift offshore again by the weekend as the ridge rebuilds. Localized dense fog continues nightly across the interior valleys through the weekend with the potential for more fog to become more widespread across the interior valleys starting Thursday night.
(18z TAFS) Issued at 903 AM PST Mon Jan 19 2026
Fog and stratus continue to mix out across the interior East Bay valleys with lingering impacts at CCR for the next couple of hours. Winds will remain light to gentle with a weak onshore breeze near the coast and offshore winds persisting inland. The TAF sites remain VFR through the day, with fog and stratus return to the North and East Bay valleys tonight with haze expected at LVK. High resolution model data depicts some chance for stratus development near LVK and in the San Francisco Bay tonight, but this is a low confidence forecast at this time.
Vicinity of SFO, VFR through the day. High resolution model output is attempting to place a patch of stratus within the southern San Francisco Bay, but impacts to the terminal are not expected. Winds remain light with offshore flow lingering through the morning until mild onshore flow develops this afternoon.
SFO Bridge Approach, Similar to SFO.
Monterey Bay Terminals, VFR through the TAF period. Light north to northwest winds through the afternoon, with breezy valley drainage winds developing overnight.
(today through Saturday) Issued at 844 AM PST Mon Jan 19 2026
Light to gentle northerly breezes persist across the waters this week. Slight increase in winds over the outer waters by late week as the large scale weather pattern begins to shift. Moderate period northwesterly swell enters the waters mid week, peaking Tuesday night into Wednesday morning.
Ca, None. PZ, None.
