textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1200 PM PST Sat Dec 6 2025

- Benign conditions through the next seven days with no precipitation expected and a gradual warming trend

- Impacts from Tule Fog continue in the North Bay and interior East Bay valleys, with potential for expansion across the rest of the Bay Area tonight

- Next chance for rain towards the middle of the month

SHORT TERM

Issued at 1200 PM PST Sat Dec 6 2025 (This evening through Sunday)

The current satellite image shows dissipating stratus across the Santa Clara Valley and the San Francisco Bay Shoreline, while the City and the valleys of the North Bay and interior East Bay remain socked in the spillover from the Tule Fog across the Central Valley. Towards the western parts of Sonoma and Marin counties, the Tule Fog spillover merges with marine layer stratus. The trend of the last couple of days has been the models struggling to accurately reflect the evolution of the Tule Fog in the North and East bay valleys. Model output shows the stratus deck beginning to dissipate over the North Bay valleys now, but that does not appear to be happening. I have tamped down the highs for today and tomorrow across the Bay Area in response to the model's struggles. The current forecast has today's highs in the upper 50s across the Bay Area valleys, with central and eastern Contra Costa County and far eastern Alameda County seeing highs in the lower to middle 50s. This does assume that the stratus does eventually mix out this afternoon, and if the stratus lingers through the day, the North and East bay valleys might not get out of the 40s. Tomorrow's forecast currently has the highs warming by a couple of degrees, within a couple degrees of 60 for most of the area, but this is highly dependent on how the Tule Fog evolves tonight into Sunday morning, and could also need to be dropped if the stratus sticks around long enough tomorrow.

Meanwhile, over in the Central Coast the skies are clear, have remained generally clear this morning, and will remain clear during the afternoon and evening hours. Model output is showing some possibility for stratus to develop in the Monterey Bay region and northern Salinas Valley tonight. While is some reason to second- guess the model output, for the reasons stated above, those reasons lean towards more stratus being present than the current forecast. However, any influence from the Tule Fog will be limited to the far eastern reaches of San Benito and southern Monterey Counties, where the Gabilan Range abuts the Central Valley. Highs in the Central Coast reach the middle to upper 60s in the inland valleys, to the lower to middle 60s closer to Monterey Bay, perhaps into the lower 70s in some of the sheltered valleys within the Santa Lucia and Gabilan ranges.

LONG TERM

Issued at 1200 PM PST Sat Dec 6 2025 (Sunday night through next Friday)

Ridging will dominate the weather patterns through the rest of the 7- day outlook, enabling a gradual warming trend across the region. The highs will peak around the later part of the upcoming work week with highs in the inland valleys reaching the middle 60s to middle 70s, around 8 to 13 degrees above the seasonal average. As with the short term forecast, the biggest source of uncertainty will be how the Tule Fog develops every night and morning, impacting the temperatures across the North and East Bay valleys. The deterministic forecast has the East Bay interior valleys remaining in the lower to middle 60s, but depending on how the Tule Fog evolves the temperatures could easily vary by around 10 degrees on either side of the current forecast.

A couple of storm systems will approach the West Coast during the 7- day outlook, but the ridging pattern will deflect the brunt of the storms to the Pacific Northwest and leave us with a chance of drizzle in the coastal waters while land areas remain dry. Longer range model guidance suggests a possible change in the weather pattern towards the middle of the month. Ensemble model cluster analysis continues to show some of the model members (somewhere around 30-40% of the ensemble members) depicting a breakdown of the ridge. however, most of the ensemble members and the ensemble means point to the ridge persisting over the western United States, or flattening out into a zonal flow pattern. Uncertainty remains rather high in this part of the forecast and we will keep an eye on what the trend from later model runs turns out to be.

AVIATION

(18Z TAFS) Issued at 940 AM PST Sat Dec 6 2025

LIFR to IFR conditions across much of the Bay Area this morning, while VFR conditions prevail at the Monterey Bay terminals. Low ceilings and/or visibilities are forecast to improve by around 20Z and give way to mostly VFR conditions. Onshore winds increase by mid- to-late afternoon across the San Francisco Bay and Monterey Bay terminals. High confidence for low ceilings and/or visibilities for the North Bay and East Bay with moderate confidence for the Bay Area terminals late tonight through Sunday morning. Moderate to high confidence for VFR conditions to prevail through much of that TAF period for the Monterey Bay terminals. Low clouds and/or fog look to improve by midday Sunday.

Vicinity of SFO...IFR conditions across much of the region this morning. Conditions are forecast to improve by 19Z-20Z and give way to VFR throughout the remainder of the afternoon. Moderate confidence for IFR conditions to return either late tonight or early Sunday morning as wind speeds turn more offshore. Onshore winds are forecast by Sunday afternoon with VFR conditions.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR through the TAF period. Light to southerly winds prevail this morning and are forecast to become onshore by early-to-mid afternoon. Winds diminish overnight and become southerly early Sunday morning.

MARINE

(Today through Thursday) Issued at 845 AM PST Sat Dec 6 2025

Fresh northwesterly winds persist through this weekend and into the middle of next week. Strong to near gale force gusts will be possible through this weekend. Moderate seas with wave heights 6 to 8 feet across the outer waters this weekend. A new, long period northwesterly swell is anticipated by Wednesday of next week.

MTR WATCHES/WARNINGS/ADVISORIES

CA...Coastal Flood Advisory until 3 PM PST Sunday for CAZ006-506-508- 529-530.

PZ...Small Craft Advisory from 3 PM to 9 PM PST Sunday for Pigeon Pt to Pt Pinos 0-10 nm.

Small Craft Advisory until 9 PM PST this evening for Pt Pinos to Pt Piedras Blancas 0-10 nm.

Small Craft Advisory from 9 AM Sunday to 3 AM PST Monday for Pt Pinos to Pt Piedras Blancas 0-10 nm.

Small Craft Advisory until 3 AM PST Sunday for Pigeon Pt to Pt Pinos 10-60 NM.

Small Craft Advisory from 9 AM to 9 PM PST Sunday for Pigeon Pt to Pt Pinos 10-60 NM.