Swell Matrix

Area Forecast Discussion

National Weather Service San Francisco CA

1220 pm PST Fri Jan 2 2026

Short Term

, Issued at 1218 PM PST Fri Jan 2 2026 (This evening through Saturday)

It has been fairly quite late this morning and is expected to remain so through the afternoon ahead of our next approaching system that is due to arrive late this evening and through Saturday morning. Southerly winds are forecast to increase this afternoon and remain gusty through at least Saturday afternoon. Sustained southerly winds of 15-25 mph with gusts up to 50 mph (locally stronger in the highest elevations) will remain possible through Saturday afternoon along the coast and in the higher terrain. Isolated thunderstorms are also possible late this evening and into early Saturday morning as surface based CAPE reaches up to 250 J/kg, most notability around the North Bay. Along with this, as the main rain band moves across the region it will be capable of producing moderate to heavy rainfall.

Isolated to scattered thunderstorms are likely Saturday a colder airmass drops southward across the region in wake of the earlier frontal passage. This is when forecast models suggest 250-750 J/kg of surface based CAPE. The greatest potential looks to be over the North Bay were we are expected the higher end of the above mentioned values will be placed late Saturday morning and into the evening. Thus, cannot rule out landfalling water spouts across this region. This is also where there is a Marginal Risk for severe weather with a general mention from the Storm Prediction Center across the remainder of the region.

Long Term

..issued at 1218 PM PST Fri Jan 2 2026 (Saturday night through next Thursday)

Thunderstorm potential will continue into Monday as reinforcing cold fronts move through the region. The greatest potential currently looks like early Sunday morning through the afternoon and again Monday afternoon. Given the breaks between these systems, we don't currently anticipate widespread flooding. However, any heavier shower or thunderstorm will be capable of producing heavy rain, small hail, and the potential for funnel clouds/water spouts.

Conditions look to remain cool and unsettled through the first half of next week, yet not nearly as wet as late this week and into to the weekend. There remain differences in the ensemble guidance making things difficult to pinpoint this far out. However, there is good confidence that we will trend drier and cooler than normal for late next week and into the following weekend (January 10-11). This is also being captured by the 6-10 day outlook from the Climate Prediction Center.

Aviation

(18z TAFS) Issued at 952 AM PST Fri Jan 2 2026

Currently VFR but expect unsettled weather to develop throughout the day with an atmospheric river arriving tonight. Winds strengthen late this morning/early this afternoon with gusts peaking between 30 to 35 knots tonight. Locally higher gusts to around 40 knots are expected along the coastline and within valleys. Rain chances increase this evening into tomorrow morning with moderate to heavy rain expected as the main rain band rolls through overnight. There is some potential for low level wind shear but, in agreement with the previous forecaster, there looks to be enough mixing downwards of stronger winds so as to prevent widespread LLWS. After the main rain band moves through, scattered light to moderate showers are expected tomorrow morning/afternoon. There is a 15-20% chance of thunderstorms both within the main rain band and in scattered showers continuing on Saturday. Visibilities are on the more pessimistic side in the TAFs with lower visibilities supported by locally moderate to heavy rain and strong winds. There is the potential for visibilities to drop even further than currently listed in the TAF if a particularly strong cell moves over the TAF site.

Vicinity of SFO, Moderate rain, lowered visibilities, and strong winds will impact SFO overnight into tomorrow. Winds strengthen this evening with gusts to around 38 knots expected overnight into tomorrow. The main rain band will arrive late this evening bringing moderate to at times heavy rain before transitioning to moderate showers early Saturday morning. Winds decrease mid Saturday morning but conditions will remain gusty before strengthening again later in the day. Guidance indicates some potential for ceilings to lower below 3000 ft at the end of the TAF period but confidence is low.

SFO Bridge Approach, Strong, gusty winds are expected over the southern SF Bay which may bring low level wind shear concerns to the SFO Bridge Approach. Current thinking is that there will be enough mixing of strong winds within the lower levels of the atmosphere to reduce LLWS concerns but it remains a possibility. Otherwise, similar to SFO.

Monterey Bay Terminals, Winds strengthen this afternoon/evening with gusts to around 30-35 knots expected overnight. Periods of moderate rain and moderate showers are expected overnight as a strong cold front passes through the region. Winds decrease by mid tomorrow morning with showers decreasing from moderate to light. Visibilities may drop further than currently listed in the TAF if a strong cell moves directly over the airport. Any additional drops in visibility are expected to be temporary.

Marine

(today through Wednesday) Issued at 904 AM PST Fri Jan 2 2026

Gale force winds have developed over the northern waters and will spread across the rest of the coastal waters today. Localized storm force winds are possible tonight across the northern outer waters. Winds diminish Saturday with gale force winds continuing for the northern waters and strong to near gale force winds elsewhere. Moderate rain and a slight chance of thunderstorms continues through the weekend with light rain expected to continue through early next week.

Beaches

Issued at 1218 PM PST Fri Jan 2 2026

A Coastal Flood Warning is in effect for the San Francisco Bay through Saturday. A Coastal Flood Advisory is in effect for the Pacific Coast and Monterey Bay through Sunday. Perigean spring tides (king tides) will impact the region through Sunday. This is due to the combination of the full moon on 1/3, lunar perigee on 1/1, and perihelion on 1/3. In other words the earth, Sun and moon are lined up and close to each other. In addition to the high astronomical tide, the incoming low pressure system will bring strong southerly winds, generating some storm surge, particularly on Saturday morning. The combination of these factors will bring moderate coastal flooding to the low-lying areas near shorelines and tidal waterways during high tide through Sunday.

On Friday, the San Francisco tidal gauge recorded 2.26 ft of inundation. Looking ahead, high tide is expected to be 2.5 ft above normal at 10:26 AM Saturday and 1.9 ft above normal at 11:18 AM Sunday. These predictions include up to 1.3 feet of storm surge that will enhance the astronomical tide and flooding threat. A reasonable worse case scenario (10% exceedance chance) is 2.7 ft of inundation on Saturday. The all time record is 2.8 ft from 1/27/1983. 2.5 ft hasn't been reached since 1998. High tide varies up to 90 minutes earlier or later along the Pacific Coast and through the San Francisco Bay, respectively.

Watches, Warnings, Advisories

Ca, Coastal Flood Warning until 2 PM PST Saturday for CAZ006-506-508.

Wind Advisory until 1 PM PST Saturday for CAZ006-502>505-509-512- 514>518-528>530.

Coastal Flood Advisory from 2 PM Saturday to 2 PM PST Sunday for CAZ006-506-508.

Coastal Flood Advisory until 2 PM PST Sunday for CAZ505-509-529- 530.

PZ, Small Craft Advisory until 3 AM PST Saturday for SF Bay N of Bay Bridge.

Small Craft Advisory until 9 PM PST this evening for Mry Bay.

Gale Warning from 9 PM this evening to 3 AM PST Saturday for Mry Bay.

Gale Warning until 3 AM PST Saturday for Pigeon Pt to Pt Pinos 0- 10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0- 10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

Gale Warning until 9 AM PST Saturday for Pt Pinos to Pt Piedras Blancas 0-10 nm.

Gale Warning until 3 PM PST Saturday for Pt Arena to Pt Reyes 10- 60 NM.

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