Swell Matrix

Area Forecast Discussion

National Weather Service San Francisco CA

953 pm PST Fri Jan 23 2026

Short Term

, Issued at 1209 PM PST Fri Jan 23 2026 (This evening through Saturday)

Low clouds linger across much of the lower elevations across the region this afternoon as the return of a ~1500 ft marine layer returned overnight. In addition, tule fog from the Central Valley as pushed westward into the East Bay Valleys. By mid afternoon, mostly sunny sky conditions are forecast expect for locations near the coast where the marine layer persists.

Expecting offshore winds to develop across the higher elevations of the North and East Bay valleys tonight and persist into Saturday. Localized gust may exceed 50 mph in some of the peaks across the region. This will dry things out considerably in these areas which may also mix down into the valleys on Saturday. However, winds are not forecast to be strong in the lower elevations. Afternoon humidity values are likely to fall below 20% in the higher terrain.

Saturday, we are expecting offshore winds to persist in the higher terrain. This offshore flow will work to compress the marine layer and essentially completely mixing it out. Thus, a slight warm up in temperatures can be expected with low to mid 60s for much of the region.

Long Term

..issued at 1209 PM PST Fri Jan 23 2026 (Saturday night through next Thursday)

Offshore winds look to diminish Saturday night into Sunday morning, yet will still be moderate in the higher terrain. Therefore, low clouds cover and/or fog will have a difficult time developing early Sunday morning with continued offshore flow aloft. However, high clouds will will begin to spread in from the west by that time.

From the previous forecaster: "The ridge looks to flatten into Sunday evening, with a zonal jetstream pattern taking its place, and offering more onshore flow. However the jetstream looks to snap back to a quick ridge into the next work week. This means temperatures will and some bounces up and down by a few degrees, and low cloud formation will be spotty.

Despite the quick ridge development, high clouds look to move through the region as a trough develops to the west. The trough formation is well-argeed upon between the longer term models, but the trajectory is a matter of debate. More models point to a cold front, and maybe a weak low pushing through the area, bringing good chances for widespread moderate rains by the mid week. However, the GFS and its ensemble members seem keen on this trough getting pushed up against the ridge ahead of it, and placing all the moisture well to the north. The GFS output looks a bit less firm than other models and the national blend, but is something to keep in mind as the longer term models update. For now, the official forecast places rain chances in the middle of the next work week along the initial front with additional chances possible beyond the forecast period."

Aviation

(06z TAFS) Issued at 953 PM PST Fri Jan 23 2026

Fairly expansive cloud cover across the Bay Area and Central Coast this evening. Starting to see some visibility fluctuations across the North Bay and East Bay. CIGs and visibility are expected to drop overnight with fog developing across the valleys. Providing uncertainty to the forecast is the arrival of moderate to strong offshore winds across the higher elevations. This should bring in much drier air to the region and subsequently cause cloud cover to be significantly reduced. HREF guidance shows a sharp drop off in the areal extent of cloud cover starting 12-13Z which is around when winds pick up. Went with a mixture of earlier clearing times (closer to 15-16Z) and late morning clearing times (17-18Z). Winds strengthen to between 10-15 knots during the day before easing overnight.

Vicinity of SFO, Currently MVFR at SFO with low to moderate confidence that it will persist past 10Z. For now kept MVFR conditions as a tempo as all guidance suggests it will clear by 10/11Z. Winds remain variable overnight before becoming northeasterly to northerly during the day. Winds strengthen to around 8-10 knots before diminishing again overnight.

SFO Bridge Approach, Similar to SFO.

Monterey Bay Terminals, MVFR with low potential for IFR conditions to develop. Not seeing any indicators of fog developing and or significant drops in visibility at MRY or SNS tonight so have pulled up forecast visibilities for SNS. Ceilings look to improve as early as 15/16Z. Confidence is slightly higher that SNS will clear by 16Z while MRY clears closer to 17Z. Winds remain NW to N throughout the day before diminishing and becoming variable overnight.

Marine

(tonight through next Thursday) Issued at 953 PM PST Fri Jan 23 2026

Fresh to locally strong gusts continue across the northern outer waters tonight before diminishing to a moderate to fresh breeze early Saturday. Wave heights are currently subsiding across the coastal waters and will subside below 10 feet by early Saturday. Improved wind and sea conditions will persist through at least mid week.

Watches, Warnings, Advisories

Ca, None. PZ, Small Craft Advisory until 3 AM PST Saturday for Pt Arena to Pt Reyes 10-60 NM.

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