Swell Matrix

Area Forecast Discussion

National Weather Service San Francisco CA

448 am PDT Fri Sep 25 2026

Short Term

, Issued at 1158 PM PDT Thu Sep 24 2026 (Tonight through Saturday)

A cool front will sweep southward across the forecast area Friday morning. The front will bring coastal low clouds Friday morning before mixing out during the day. Daytime highs will be cooler with highs ranging from the 60s to lower 70s coastside to the mid 70s and 80s inland. Additional cooling arrives for Saturday with daytime highs in the 60s/70 at the coast, mostly 70s inland except in the 80s across the southern interior of Monterey and San Benito counties.

Long Term

..issued at 1158 PM PDT Thu Sep 24 2026 (Saturday night through next Thursday)

There's good agreement in the global models showing a progressive pattern across the Pacific into the western CONUS late in the weekend through mid next week. This is a signature of a strong north hemispheric meridional temperature gradient, robust polar jet stream and subtropical jet stream winds, wind shear and low pressure system(s) development. With both jet streams across the eastern Pacific working in unison through the forecast period, this greatly increases the chance we see reinforcing drier mid- latitude wind flow suppressing tropical activity far to our south during this timeframe.

The cooler weather lasts through Monday before we return to a warming trend Tuesday through Thursday. 500 mb ridging returns during this time with breezy to gusty coastal northwesterly winds and dry weather prevailing.

Aviation

(12z TAFS) Issued at 430 AM PDT Fri Sep 25 2026

Hybrid marine layer this morning as some clouds formed ahead of a cold front. ACARs and sounding puts the inversion near 1000-1200 feet. Pretty shallow with IFR to LIFR conditions underneath it. Biggest impacts will be HAF, inside SF Bay, and Salinas Valley. Could see some sunrise clouds arrive for SJC as they filter in from the N. Put a tempo for SJC through 15Z. Behind the front winds increase and mixing out the low clouds. Overall conf is moderate for this morning.

Vicinity of SFO, LIFR impacts through 17-18Z. VFR this afternoon. Stronger onshore push behind the front with gusts over 20kt poss.

SFO Bridge Approach, Similar to SFO.

Monterey Bay Terminals, LIFR for SNS due to low fog through 16Z. MRY is VFR but nearby clouds have a 30 pct chc of impacts after sunrise. VFR this afternoon.

Marine

(today through Wednesday) Issued at 430 AM PDT Fri Sep 25 2026

A passing weak cold front will bring fresh to strong northerly breezes into the weekend. Near gale force gusts are possible across Monterey Bay south to Big Sur Sunday afternoon and evening. Tropical storm activity producing long period southerly swell begins to increase for the beginning of next week.

Watches, Warnings, Advisories

Ca, None. PZ, Small Craft Advisory from 9 AM this morning to 9 PM PDT this evening for Mry Bay.

Small Craft Advisory from 9 AM this morning to 3 AM PDT Saturday for Pigeon Pt to Pt Pinos 0-10 nm-Pt Arena to Pt Reyes 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

Small Craft Advisory until 3 PM PDT Saturday for Pt Pinos to Pt Piedras Blancas 0-10 nm.

Small Craft Advisory from 9 AM this morning to 3 PM PDT Sunday for Pt Arena to Pt Reyes 10-60 NM.

Small Craft Advisory from 9 AM this morning to 3 PM PDT Saturday for Pigeon Pt to Pt Pinos 10-60 NM.

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