Swell Matrix

Area Forecast Discussion

National Weather Service San Francisco CA

352 am PST Thu Jan 8 2026

Short Term

, Issued at 159 AM PST Thu Jan 8 2026 (Today and tonight)

Some rain showers associated with a cold front are quickly sweeping from northwest to southeast across the region. Accumulation has been a few hundredths at most with wind gusts in the 40-50 mph range in the higher terrain of the North Bay and East Bay. Activity is expected to be wrapped up by the afternoon which will give way to below normal temperatures and clear skies.

Long Term

..issued at 159 AM PST Thu Jan 8 2026 (Friday through Wednesday)

Surface high pressure will waste no time building in the cold front's wake, initially into the California/Oregon border before ultimately into the Great Basin. Simultaneously, a coastal trough will develop off the California Coast which will facilitate offshore flow. Calm, clear, and cool conditions with long nights is a recipe for radiational cooling. The Extreme Cold Watch has been upgraded for the Thursday night period from 1 AM to 9 AM Friday. An Extreme Cold Warning is in effect for the Eastern Santa Clara Hills and Interior Monterey and San Benito Counties. In these locations, sub- freezing temperatures in the mid 20s to low 30s can be expected. Most of the rest of the Bay Area and Central Coast are under a Cold Weather Advisory during the same time. In these locations, temperatures are expected to be in the low to mid 30s. As a reminder, the Extreme Cold Watch, Cold Weather Advisory, and Extreme Cold Warning have recently been adopted to address cold impacts to humans throughout the year. Friday and Saturday are expected to be the coldest mornings of the period - the Central Coast is forecast to be coldest Friday morning while the Bay Area is forecast to be coldest Saturday morning. It's important to put all of this in context. 850 millibar temperatures can be used as a proxy for the air mass. At 12Z Friday, the 850 millibar temperature is forecast to be 8 degrees Celsius which is above the daily mean of 6.8 degrees Celsius for the date and time. This tells me that we are not dealing with a cold air mass. A lot of people have been asking if any record low temperatures will be broken and the answer is no as we simply do not have the air mass to support it and we have some very low temperatures to contend with. For example, SJC's daily record lowest minimum temperature record is 22 degrees set all the way back in 1937 - they haven't gotten below 30 degrees since December 2013. Suffice it to say that it's going to be cold, but not record breaking cold. Confidence is high that an anomalously high amplitude upper-level longwave ridge will meander over the West Coast through Wednesday before retrograding west out over the Eastern Pacific Ocean. This will result in a warming trend of about 20 degrees in the next seven days. Overnight temperatures will respond accordingly, slowly beginning to warm up Sunday morning and continuing that trend through the forecast period.

Aviation

(12z TAFS) Issued at 336 AM PST Thu Jan 8 2026

A few lingering showers, with temporary lower cigs, continue to move through the region N to S. Thankfully, coverage of shower activity is rapidly decreasing and will do so through sunrise. Gusty northerly winds have also ease overnight, but still holding onto some gusts through sunrise as well. There after, a building drier airmass with offshore flow will lead to VFR.

Vicinity of SFO, A few-sct cigs through early this morning AOA 2500-3000 feet. VFR with SKC this afternoon.

SFO Bridge Approach, Same as SFO

Monterey Bay Terminals, VCSH through 15Z. VFR this afternoon and tonight.

Marine

(today through Tuesday) Issued at 336 AM PST Thu Jan 8 2026

A passing cold front will bring gusty northerly winds and scattered showers to the coastal waters and bays through early Thursday afternoon. A building northwesterly swell will arrive Thursday leading to a rough sea state with shoaling near the coast, harbor entrances, and bars. Winds and seas will ease Friday into the weekend.

Beaches

Issued at 350 AM PST Thu Jan 8 2026

High Surf Advisory remains in effect through 10 pm Friday PST. Expect large breaking waves up to 22 feet, strong rip currents and sneaker waves from coastal Sonoma county to coastal Monterey county, excluding the northern Monterey Bay shoreline where a Beach Hazards Statement will be in effect. Large breaking waves can overpower swimmers resulting in significant physical injury and increase the risk of drowning.

Beach Hazards Statement remains in effect through Friday evening for the northern Monterey Bay shoreline. Expect hazardous beach conditions with strong rip currents, sneaker waves, and breaking waves up to 15 feet. This will result in dangerous conditions along the shoreline.

Stay off of jetties, piers, rocks, and other waterside infrastructure. Remain out of the water to avoid hazardous surf and NEVER turn your back on the ocean. Monitor local weather, surf and tide forecasts at www.weather.gov/mtr.

Watches, Warnings, Advisories

Ca, High Surf Advisory until 10 PM PST Friday for CAZ006-505-509-530.

Cold Weather Advisory from 1 AM to 9 AM PST Friday for CAZ502- 506-510-512-513-515-528>530.

Extreme Cold Warning from 1 AM to 9 AM PST Friday for CAZ514- 516>518.

Beach Hazards Statement through Friday evening for CAZ529.

PZ, Small Craft Advisory until 3 PM PST this afternoon for Mry Bay.

Small Craft Advisory until 3 AM PST Friday for Pigeon Pt to Pt Pinos 0-10 nm-Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

Small Craft Advisory until 3 PM PST Friday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.

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