textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1201 PM PDT Fri Sep 11 2026

- Temperatures near seasonal averages through the next week

- Breezy onshore winds this weekend

SHORT TERM

Issued at 1201 PM PDT Fri Sep 11 2026 (This evening through Saturday night)

The return of the marine layer (around 1600 feet per 12Z OAK Upper Air Sounding) resulted in widespread coverage of stratus this morning, with the exception of the East Bay interior valleys. Since then, clouds are quickly retreating to the coast and are forecast to linger off of the Central Coast for much of the day. However, a weak frontal boundary approaching the North Bay is likely to bring a return of clear skies off of the North Bay coast this afternoon.

Despite mostly sunny sky conditions across the interior, today will be much cooler than previous days as the region remains in between mid/upper level cut-off low off of the British Columbia coast and high pressure confined to southern California, Nevada, and Arizona. Less confidence tonight in the amount of stratus that returns to the region as the aforementioned frontal boundary moves southward and then weakens.

The cut-off low will shift southward before moving into the Pacific Northwest Saturday night and into Sunday. As such, westerly to northwesterly winds will increase tomorrow afternoon and persist through Saturday night ahead of yet another frontal boundary. The strongest wind gusts will be between 25 to 35 mph with favored gaps, passes, and coastal regions gusts up to 45 mph. This cold front will sweep across the North Bay and Bay Area Saturday night into Sunday with no measurable precipitation forecast.

LONG TERM

Issued at 1201 PM PDT Fri Sep 11 2026 (Sunday through next Thursday)

In wake of the frontal passage, offshore flow is forecast from Sunday night and into Monday night as 925 mb winds become northerly to northeasterly. However, the offshore flow is not forecast to be much greater than 20 kt (23 mph) at 925 mb, limiting fire weather concerns. Onshore winds are forecast to persist in the lower elevations with the strongest in the early afternoon and through the evening hours. Thus, the marine layer looks to hold around 1500 feet in depth through the weekend. As mentioned in the Fire Weather section of the AFD below, areas above the marine layer often experience nocturnal drying (during the overnight hours). That will be the case during this offshore event. The trough axis is forecast to move into the northern Rockies and the 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 next week. This will give way to temperatures warming 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.

AVIATION

(18Z TAFS) Issued at 1030 AM PDT Fri Sep 11 2026

Stratus coverage is decreasing across the Bay Area but persists directly along the coast and along the Monterey Peninsula. Cloud cover is expected to continue decreasing through the remainder of the morning with low to moderate confidence in the timing of stratus return tonight. HREF keeps stratus more confined to the coast and along the SF Bay shoreline with the marine layer ~1000 ft. The marine layer did overperform this morning (12Z OAK sounding reported it to a depth of 1500 ft) which resulted in more widespread cloud cover. If the marine layer again overperforms tonight then we may see more expansive cloud cover than currently forecast. Generally expecting IFR to LIFR CIGs with lower CIGs expected along the coast. Gusty onshore winds return this afternoon with winds decreasing overnight. There is an early signal for gusts between 25 to 30 knots on Saturday so have started including after 18Z Saturday for 30 hour TAF sites.

Vicinity of SFO...VFR persists through tonight with a low to moderate chance for stratus to impact the airport overnight. Confidence is low that stratus will reach SFO as the latest guidance keeps stratus more confined to the coast and mainly impacting OAK in the SF Bay. If stratus does reach SFO it will likely be early Saturday morning and clear by noon at the latest. Strong onshore winds are expected Saturday afternoon/evening with gusts to around 30 knots, potentially up to 35 knots, likely.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Stratus has cleared at SNS but is persisting over MRY. Guidance shows some potential for stratus to persist at MRY through the day but there may be a brief period of clearing/VFR conditions this afternoon. IFR-LIFR stratus returns overnight and persists through the end of the TAF period. Breezy onshore winds return during the day before decreasing overnight.

MARINE

(Today through Wednesday) Issued at 905 AM PDT Fri Sep 11 2026

A moderate to fresh NW breeze will increase over the next 24 hours, with a strong breeze to develop by early Sunday and continue into next week. Near gale force to gale force winds 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. Hazardous conditions for small craft will prevail late this weekend through mid next week. Seas are currently moderate and will build to rough by Monday in response to the stronger winds.

FIRE WEATHER

Issued at 429 AM PDT Fri Sep 11 2026

A new weather pattern will influence conditions over the Timber and Plaskett Fires in Monterey County. The marine layer has returned and is 1,600 feet deep as measured by the 12Z balloon. This height should be fairly consistent through the day before some expansion this weekend as the trough moves through. While the marine layer brings much cooler and more humid conditions to the coast, areas above the marine layer often experience nocturnal drying as the dry air above the clouds rolls in simultaneously with the low clouds. In the late morning the clouds will mix out as the layers become less stratified, often increasing dew point during the warmest part of the day.

Flynn

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...Small Craft Advisory from 9 AM to 3 PM PDT Saturday for Mry Bay- Pigeon Pt to Pt Pinos 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm- SF Bay N of Bay Bridge.

Small Craft Advisory until 3 PM PDT Saturday for Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 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 9 AM PDT Saturday for Pt Arena to Pt Reyes 10-60 NM.