Swell Matrix

Area Forecast Discussion

National Weather Service San Francisco CA

1205 pm PDT Sat Sep 12 2026

Short Term

, Issued at 1201 PM PDT Sat Sep 12 2026 (This evening through Sunday night)

As mostly sunny skies have returned to the region, we are expected temperatures to warm into the 60s to lower 70s along the northwest facing coastal locations and low to upper 70s around the Santa Cruz region, bayshore, and coastal adjacent valleys. Meanwhile, interior valleys are forecast to reach into the upper 70s to mid 80s with the warmest interior valleys of the Central Coast reaching into the low 90s. Onshore wind gusts are forecast to reach between 25 to 35 mph in the favored gaps, passes, and coastal/higher elevation regions gusts up to 45 mph. This is ahead of a dry frontal boundary which is expected to move through the North Bay late this evening and then across the Central Coast Sunday morning. Moderate to high confidence that low clouds will not spread inland overnight into Sunday morning (patchy at best), similar to this morning. However, the marine layer looks to hover between 1,500 and 2,000 feet through the night. By Sunday afternoon, the front is forecast to be south of the region with cooler temperatures in the higher elevations while slightly cooler for the lower elevations. Onshore winds will increase once again tomorrow afternoon and evening with gusts potentially exceeding those forecast for today, but only by 5 to 10 mph. Aloft, a light to gentle offshore breeze (with occasionally moderate gusts) is forecast to develop in the higher terrain as the mid/upper level trough axis shifts into the northern Rockies. These winds are not forecast to be overly strong, which will help limit fire weather concerns.

Long Term

..issued at 1201 PM PDT Sat Sep 12 2026 (Monday through next Friday)

The trough axis is forecast to move into northern Plains early next week, diminishing the offshore wind potential. Lingering troughiness along the West Coast will maintain cooler than average temperatures for much of the week ahead. As such, temperatures are forecast to warm into the 60s to lower 70s along the northwest facing coastal locations and low to upper 70s around the Santa Cruz region, bayshore, and coastal adjacent valleys. Meanwhile, interior valleys are forecast to reach into the upper 70s to mid 80s with the warmest interior valleys of the Central Coast reaching into the low 90s. Overnight and morning low clouds are expected to reach inland before mixing out by the afternoon hours as well through the extended forecast period.

Aviation

(18z TAFS) Issued at 1036 AM PDT Sat Sep 12 2026

VFR across the region with low confidence that stratus will return tonight. Guidance is showing a largely drier airmass moving in tonight which is decreasing confidence that we will see widespread stratus coverage. More favorable conditions for localized fog/stratus development exist along the coast where buoys are showing an upwards transfer of heat/moisture from the sea to the air (SST are warmer than air temperatures above the buoy). Expect gusty winds today with widespread gusts between 25 to 35 knots. Locally stronger gusts are possible in areas where terrain promotes wind funneling.

Vicinity of SFO, VFR through the TAF period. Gusty onshore winds are expected today with gusts between 25 to 35 knots forecasted this afternoon into the evening. Winds decrease slightly overnight but strengthen again by Sunday morning. The SFO-WMC gradient peaks around +13 mb today which correlates to strong onshore winds.

SFO Bridge Approach, Similar to SFO. Strong onshore winds are expected this afternoon/evening with gusts to around 35 knots possible.

Monterey Bay Terminals, VFR. Low confidence that stratus will return tonight but if it does return it likely will not be until after 12Z. Given the low confidence, have only included a tempo for tonight's stratus coverage after 12Z. Gusty onshore winds peaking around 25 knots are expected today before diminishing overnight. Breezier conditions are expected again tomorrow but winds should be weaker than those observed today.

Marine

(today through Thursday) Issued at 856 AM PDT Sat Sep 12 2026

Hazardous conditions for small craft prevail this weekend through the middle of next week. Winds increase today with a strong breeze to develop by early Sunday and continue into the middle of next week. Widespread near gale force gusts are likely Sunday into early Monday with gale force gusts are expected along the inner waters from Pigeon Point to Point Piedras Blancas, the Monterey Bay, and in portions of the San Francisco and San Pablo Bays. Moderate seas will build, becoming rough by Monday in response to the stronger winds.

Watches, Warnings, Advisories

Ca, None. PZ, Small Craft Advisory until 9 AM PDT Sunday for SF Bay N of Bay Bridge.

Small Craft Advisory from 3 PM to 9 PM PDT Sunday for SF Bay N of Bay Bridge.

Small Craft Advisory until 3 PM PDT Sunday for Mry Bay-Pigeon Pt to Pt Pinos 0-10 nm.

Gale Warning from 3 PM to 9 PM PDT Sunday for Mry Bay-Pigeon Pt to Pt Pinos 0-10 nm.

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

Small Craft Advisory until 9 PM PDT this evening for Pt Pinos to Pt Piedras Blancas 0-10 nm.

Gale Warning from 9 PM this evening to 9 PM PDT Sunday for Pt Pinos to Pt Piedras Blancas 0-10 nm.

Small Craft Advisory from 3 PM Sunday to 3 AM PDT Monday for Pt Arena to Pt Reyes 10-60 NM.

Small Craft Advisory until 3 AM PDT Monday for Pigeon Pt to Pt Pinos 10-60 NM.

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