Swell Matrix

Area Forecast Discussion

National Weather Service San Francisco CA

450 am PDT Thu jul 9 2026

Short Term

, Issued at 1244 AM PDT Thu Jul 9 2026 (Today and tonight)

Onshore winds are ushering stratus inland. 2.8 mb ACV-SFO and 3.0 mb SFO-SAC pressure gradients support northwest to west winds. The 500 mb high pressure system centered over southern California and northern Mexico will remain nearly stationary over the next 24 hours. Surface warming will mix out much of the stratus today by late morning and afternoon. Daytime highs today will be in the 60s coastside, 60s/70s bayside to the 80s/90s inland.

Stratus returns tonight. Lows will be in the 50s except lower to mid 60s at higher elevations tonight.

Long Term

..issued at 1244 AM PDT Thu Jul 9 2026 (Friday through Wednesday)

Global model guidance is consistent showing the 500 mb high pressure system beginning to move northeastward Friday through early next week. Daytime highs will be coolest along the coast with 60s, 60s/70s bayside and in the 80s/90s inland to the lower 100s far inland mainly over the southern interior. Night-time lows will cool to the 50s/60s.

Southerly winds aloft on the periphery of the high will transport mid-level sub-tropical/tropical moisture to our forecast area beginning Saturday night and Sunday and lasting through Tuesday night. We'll continue to monitor the potential for a temporary increase in mid level instability. At the earliest onset of moisture arriving, recent 00z guidance from the NAM and RRFS are mixed, the NAM shows pockets of instability to our southwest late Saturday night to early Sunday, while the RRFS does not show any mucape. 00z GFS continues to show essentially no mucape except occasional pockets of mid-level mucape. We'll continue to monitor the higher resolution models with each subsequent model run(s). A possible limiting factor for convection over our forecast area is 500 mb height ridging is forecast to extend west from the eastward departing 500 mb high center. If this occurs, broad anticyclonic flow will be present, however can't completely discount embedded thermal trough(s) within the broad anticyclonic flow given the height field; summer weather systems can be a complex mix in the various layers of the troposphere. There's currently good agreement in this westward extending 500 mb ridge scenario in the ECMWF and GFS, a good sign for less convective potential. At this time the potential for convection is a low confidence forecast because of the varied output seen so far. Please stay tuned to the latest updates.

Aviation

(12z TAFS) Issued at 425 AM PDT Thu Jul 9 2026

W-NW onshore flow and a more robust marine layer from earlier this evening has combined for IFR/LIFR ceilings for all locations other than KSJC, which is MVFR and the best candidate to begin clearing out by mid-morning with KLVK not far behind. Mixing in of slightly warmer temperatures later this morning should lead to stratus retreating sooner than the past few days, with most terminals lifting to VFR by late morning, except for KMRY.

Vicinity of SFO, The more westerly flow may result in KSFO ceilings lingering into early afternoon with steady fetch of stratus straight into San Francisco Bay. MVFR/IFR ceilings return around or soon after sunset.

SFO Bridge Approach, Clouds will clear earlier than the terminal.

Monterey Bay Terminals, LIFR cigs are expected to persist into late morning. Theres a 50/50 chance of a shore window of VFR by mid-afternoon, then IFR/LIFR returns after sunset through the remainder of the forecast period.

Marine

(today through Tuesday) Issued at 425 AM PDT Thu Jul 9 2026

Fresh to strong northwest winds continue, increasing to near gale force heading into the weekend. Wind driven rough seas (9-11 ft) will persist into the weekend along with a long period southerly swell.

Beaches

Issued at 425 AM PDT Thu Jul 9 2026

A Beach Hazards Statement remains in effect for Pacific coast beaches through Friday afternoon. Long period southwesterly swell will create an increased risk of sneaker waves and strong rip currents, as well as breaking waves up to 10 feet. This will be especially true for south and southwest facing beaches with moderate to steep slopes along the North Bay, San Francisco Peninsula, and Santa Cruz coasts. Sneaker waves can sweep across the shoreline without warning, pulling people into the sea from rocks, jetties and beaches. Dangerous swimming and surfing conditions and localized beach erosion can be expected. 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.

A Coastal Flood Advisory is in effect for minor high tide flooding through Thursday July 16th. The combination of a perigean spring tide (lunar perigee on 7/13 and new moon on 7/14) enhanced by 3-6 inches of additional water from thermal expansion and accumulated sea level rise since the tidal datum was established (1983-2001) will bring high tides up to 1.7 feet above normal. This will lead to minor flooding of parking lots, parks and roads with isolated closures expected. For context, in June we reached 2.0 feet above normal.

Watches, Warnings, Advisories

Ca, Beach Hazards Statement through Friday afternoon for CAZ006-505- 509-529-530.

Coastal Flood Advisory from 4 PM this afternoon to 4 AM PDT Thursday for CAZ006-506-508.

Coastal Flood Advisory from 8 PM Saturday to 4 AM PDT Wednesday for CAZ505-509-529-530.

PZ, Small Craft Advisory until 3 PM PDT Sunday for Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.

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

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

Small Craft Advisory until 3 AM PDT Saturday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.

Visit this site often? Consider supporting us with a $10 contribution.
Learn more