Swell Matrix

Area Forecast Discussion

National Weather Service San Francisco CA

1200 pm PDT Wed may 13 2026

Short Term

, Issued at 1200 PM PDT Wed May 13 2026 (This evening through Thursday)

Skies are clearing across the region with a decaying cold front, the fringes of an upper level trough coming across the Pacific Northwest, helping to mix out the lower levels across the Bay Area and Central Coast. Some patches of stratus linger across the San Mateo Peninsula and the Monterey Bay region, but these patches should mix out through the afternoon hours. High temperatures remain seasonally average to cool with temperatures in the 70s to the lower 80s in the inland valleys, the middle 60s to lower 70s close to the bays, and the upper 50s to the lower 60s near the Pacific coast. A strengthening pressure gradient will develop as a Pacific high opposes a low developing in the Great Basin, with northwesterly gusts of 25 to 35 miles per hour developing this afternoon and evening along the coast, through favorably oriented gaps and valleys, and across the ridgelines. Winds should diminish late this evening in to the post-midnight hours on Thursday.

For Thursday, mild ridging should settle into the region and allow for a gradual warming trend, with highs in the inland valleys reaching the upper 70s to the upper 80s. Some low clouds could develop on the western side of the San Mateo Peninsula into the Monterey Bay region, with the stratus dissipating through the morning as an onshore breeze forms in the afternoon, although wind speeds should not be as strong as today's winds.

Long Term

..issued at 1200 PM PDT Wed May 13 2026 (Thursday night through next Tuesday)

Temperatures on Friday should be similar to those seen on Thursday, but the winds could start picking up again as an upper level trough develops from the Gulf of Alaska into the Pacific Northwest, increasing the pressure gradient and causing gusts to rise to the 25 to 35 mph range along the coast, through gaps and passes, and at the ridgelines. Through the weekend, a part of that trough breaks off from the westerly flow and starts to stall over the Northern Rockies, further reinforcing the strong winds across the region and especially at the favored regions. On Saturday, NBM probabilities show good chances (above 80% probabilities) for wind gusts above 40 mph along the coastal regions; along the ridgelines of the Mayacama, Santa Cruz and Santa Lucia Mountains; and through the Salinas Valley between Salinas and King City. Wind Advisories may end up being necessary Friday through the weekend, as confidence in the extent and strength of the winds increases through the next couple of days. Beach Hazards Statements or High Surf Advisories may also be required due to strong and dangerous wind-driven waves.

As for temperatures, the incoming trough will interrupt the warming trend with temperatures on Saturday and Sunday dropping back into the 70s to lower 80s in the inland valleys. For the early part of next week, the warming trend will resume as upper level ridging returns to the West Coast. There continues to be some variability in the ensemble space depending on how that upper level ridging interacts with the lingering trough over the Rockies. The NBM seems to be running a little warm in that ensemble space, so in coordination with our neighbors and national centers, we've dropped the high temperature forecasts by around 3 degrees across our forecast area for the early part of next week. For next Tuesday and Wednesday, the current forecast calls for highs in the middle 80s to lower 90s in the inland valleys, the upper 70s to the middle 80s close to the Bays, and the lower to middle 60s near the Pacific coast. Judging from a close analysis of the ensemble clusters, the wiggle room for those inland highs looks to be around 3 to 5 degrees in either direction. The coastal and Bayshore highs are harder to say, particularly if the marine layer does return to those regions, as the resolution of the global ensemble models does not allow for a good depiction of those marine layer impacts.

Aviation

(18z TAFS) Issued at 1047 AM PDT Wed May 13 2026

Patchy stratus is clearing across the Bay Area and Central Coast with all sites expected to be VFR this afternoon/evening. Stratus is expected to be patchy tonight with the highest confidence in a late stratus return for coastal sites and along the bay shoreline. Wind gusts pick up rapidly this afternoon and evening with gusts to around 25-35 knots along the coast and 20-25 knots across portions of the interior. Winds decrease overnight with breezy conditions expected again during the afternoon/evening tomorrow.

Vicinity of SFO, Strong west to northwest winds are expected through this evening with gusts between 25-35 knots. Winds ease overnight but are expected to pick up again tomorrow morning/afternoon. There is a slight chance for stratus to reach SFO after 10Z but confidence was too low to include in TAF given a much drier airmass expected to move in.

SFO Bridge Approach. Generally similar to SFO but gusts look to be closer to 25-30 knots.

Monterey Bay Terminals, Stratus will continue to dissipate through late this morning with VFR expected this afternoon/evening. Moderate confidence that stratus will reach MRY late tonight but confidence is lower that it will reach SNS. Breezy west to northwest winds are expected this afternoon/evening with gusts to around 20 knots expected. Winds ease overnight with gusty winds to return tomorrow afternoon.

Marine

(today through Monday) Issued at 1047 AM PDT Wed May 13 2026

Hazardous marine conditions expected late week through the weekend. Winds will continue to increase through the work week with strong winds and near gale-force gusts possible today. Persistent gale-force winds affect the outer waters beginning Thursday, with gale force to severe gale winds expected to become widespread by Friday. Occasional storm force gusts are possible across the inner waters this weekend. Very high wind driven seas between 12 to 17 feet are expected. Winds stay hazardously strong through the weekend, but ease early to mid next week.

Watches, Warnings, Advisories

Ca, None. PZ, Small Craft Advisory until 3 AM PDT Thursday for Mry Bay.

Gale Watch from Saturday afternoon through late Saturday night for Mry Bay.

Small Craft Advisory until 9 AM PDT Thursday for Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.

Gale Warning from 9 AM Thursday to 3 AM PDT Friday for Pt Arena to Pt Reyes 0-10 nm.

Gale Watch from Friday afternoon through Sunday evening for Pigeon Pt to Pt Pinos 0-10 nm-Pt Arena to Pt Reyes 0-10 nm- Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

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

Gale Warning from 9 AM Thursday to 9 AM PDT Friday for Pt Arena to Pt Reyes 10-60 NM.

Gale Watch from Friday morning through Sunday evening for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.

Small Craft Advisory until 9 PM PDT Thursday for Pigeon Pt to Pt Pinos 10-60 NM.

Gale Warning from 9 PM Thursday to 9 AM PDT Friday for Pigeon Pt to Pt Pinos 10-60 NM.

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