Swell Matrix

Area Forecast Discussion

National Weather Service San Francisco CA

431 am PDT Mon aug 10 2026

Short Term

, Issued at 1205 AM PDT Mon Aug 10 2026 (Today and tonight)

Upper-level shortwave troughing developing off the West Coast Monday will kickoff the cooling trend. The 1,000 foot marine layer will likely remain steady, at least initially, with drizzle possible in the mornings. The aforementioned troughing will result in an increase of onshore flow with gusts up to 30 mph in the afternoon/evening through gaps/passes and across ridgelines. This will lead to elevated fire weather conditions across the higher terrain coming off the heels of very hot and dry conditions. Minor coastal flooding is expected during the highest high tide (evening/overnight) for bayshore locations along the San Francisco Bay, San Pablo Bay, and Monterey Bay through Thursday morning.

Long Term

..issued at 1205 AM PDT Mon Aug 10 2026 (Tuesday through Sunday)

A reinforcing trough Wednesday will bring widespread below normal temperatures and deepen the marine layer. Global ensemble clusters are in agreement that heights and subsequently temperatures will fall through Thursday as it digs. An increase in monsoonal/sub- tropical moisture is bringing a low (up to 10%) chance for elevated rain showers/thunderstorms with ingredients seemingly only marginal as of now. Best chances look to be Wednesday through Thursday and would likely favor the far southern and eastern parts of the area as the conveyor belt of moisture stays between troughing to the west and ridging to the east. While confidence is low, this would be a high-impact scenario with gusty outflow winds and the potential for new fire starts. It's going to be a fair fight going into the weekend between a reinforcing trough off the West Coast and a rebuilding ridge across a majority of the rest of CONUS. The official forecast has a slight warming trend into the weekend, most noticeable across the Interior Central Coast.

Aviation

(12z TAFS) Issued at 431 AM PDT Mon Aug 10 2026

Coastal stratus and fog /MVFR-IFR-LIFR/ continue to redevelop and onshore winds are at least partially ushering stratus and fog inland this morning. More recently the marine layer is showing signs of deepening to 1300 to 1800 feet. Stratus and fog will mix out by late morning with VFR prevailing through the afternoon. Stratus and fog /MVFR-IFR-LIFR/ redevelop tonight and Tuesday morning.

Vicinity of SFO, Stratus is currently north of SFO. VFR is forecast to continue at the terminal. West to northwest wind 5 to 15 knots except 15 to 25 knots in the afternoon and evening.

SFO Bridge Approach, Similar to SFO.

Monterey Bay Terminals, Stratus /IFR-LIFR/ will mix out to VFR by late morning with VFR continuing through the afternoon. Stratus /IFR- LIFR/ redevelops and moves inland tonight and Tuesday morning. West to northwest winds 5 to 15 knots.

Marine

(today through Saturday) Issued at 407 AM PDT Mon Aug 10 2026

Fresh to strong northwest winds will persist through the middle of the week with rough seas up to 12 feet over the northern outer waters and occasionally the inner waters north of Point Reyes. The San Pablo, Suisun Bays and the Delta will continue to see gusty onshore winds through early this evening. The long period southerly swells around 15 seconds will continue through much of the work week.

Watches, Warnings, Advisories

Ca, Coastal Flood Advisory until 2 AM PDT Thursday for CAZ006-506- 508-529-530.

PZ, Small Craft Advisory until 9 PM PDT this evening for SF Bay N of Bay Bridge.

Small Craft Advisory until 9 AM PDT Wednesday for Pt Arena to Pt Reyes 10-60 NM.

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