Swell Matrix

Area Forecast Discussion

National Weather Service San Francisco CA

859 am PDT Sat Mar 21 2026

Update

Issued at 855 AM PDT Sat Mar 21 2026

High clouds cover the region as a weak cold front passes through the region, with low-level stratus having mostly cleared out at the immediate coast. The current forecast remains on track with temperatures near to slightly above seasonal averages today. For more information, refer to the previous discussion.

DialH

Short Term

, Issued at 301 AM PDT Sat Mar 21 2026 (Today and tonight)

The transition from ridging and high pressure to a modest zonal flow is already affecting temperatures. A map of 24 hour temperature change shows most areas around 5 degrees cooler than this time last night, with portions of the Big Sur Coast around 20 degrees cooler as the thermal belt erodes.

The marine layer is also redeveloping, leading to some pockets of coastal fog and stratus along the coast of Monterey Co and around Half Moon Bay. The reducing pressure will allow the marine layer to expand through the morning, and hints at a weak southerly surge of stratus along the Big Sur. Areas affected by this push of stratus look to have much cooler temperatures than previous days, but this will be focused on the immediate coast.

The rest of the region will still see a notable cooldown today as the pressure reduces and slight onshore flow develops. Highs will range 5 to 15 degrees cooler than previous days, with the low 60s on the coast, 70s for areas slightly more inland, and the 80s for the more interior areas. This will still be roughly 5 to 10 degrees above average for the non-coastal areas, but will be a welcome change of pace from the hazardous, record-breaking heat of the work week.

Long Term

..issued at 301 AM PDT Sat Mar 21 2026 (Sunday through Friday)

The cooling trend continues into Sunday with highs and lows reducing by a few more degrees. But this is where our pattern looks to hold steady. Our zonal to slight ridging pattern continues through the next work week, keeping highs and lows fairly similar from day to day. Some spots in the Bay Area will see only a 3 degree difference from the warmest day to the coolest day.

Chances for coastal drizzle have fizzled out as Wednesday's cold front has pushed farther north in more recent model update. With those chances out of the forecast, it looks like it might not be until the very end of the month before chances for rain return to the forecast. Some of the extended term models still show a developing trough pushing a weak low pressure into the Bay Area into April. But even the most optimistic models only show chances for scattered light rains as this low weakens as it approaches.

Aviation

(12z TAFS) Issued at 437 AM PDT Sat Mar 21 2026

It's VFR except for patchy coastal fog and stratus /LIFR-IFR/ this morning. Gusty west to northwest winds developing later in the morning and afternoon.

Vicinity of SFO, VFR. West wind increasing to 15 to 25 knots later today and into the evening, then decreasing to 10 to 15 knots tonight and Sunday morning.

SFO Bridge Approach, Similar to SFO.

Monterey Bay Terminals, VFR except a patch or two of fog and stratus /LIFR-IFR/ this morning. West to northwest winds increasing to 10 to 20 knots today. Winds decreasing to light and variable tonight and Sunday morning.

Marine

(today through Thursday) Issued at 855 AM PDT Sat Mar 21 2026

A passing cold front will bring fresh and strong breezes with gale force gusts to the coastal water today. Strongest winds will be over the outer waters and in the Point Reyes coastal jet region. The strong winds will lead to steep fresh swell. Winds diminish and seas abate early next week then increase again mid week.

Watches, Warnings, Advisories

Ca, None. PZ, Small Craft Advisory until 9 AM PDT this morning for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm.

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

Small Craft Advisory until 3 AM PDT Sunday for Pt Reyes to Pigeon Pt 0-10 nm.

Small Craft Advisory until 3 AM PDT Sunday for Pigeon Pt to Pt Pinos 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm.

Gale Warning until 9 AM PDT Sunday for Pt Arena to Pt Reyes 10- 60 NM.

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