textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 126 AM PST Mon Dec 29 2025

- Cold overnight conditions for interior and valley locations this morning and again tonight.

- Rain returns Wednesday and lasts through the weekend.

- Coastal flooding from King Tides is expected Wednesday through Sunday.

SHORT TERM

Issued at 126 AM PST Mon Dec 29 2025 (Today and tonight)

Quiet weather continues today as an upper level low slides from the Reno/Tahoe area across central California and into the Pacific. This can clearly be seen on the water vapor satellite channel this morning, while high pressure noses into northwest California. Offshore flow dominates the current weather pattern, keeping conditions dry and even warm and windy in the terrain, especially in the North Bay. In the lower elevations, or where temperatures struggled to recover in the mountains yesterday, temperatures will be chillier. The Cold Weather Advisory remains in effect for the valleys and interior locations, the exception being the interior North Bay mountains. The coldest conditions happened yesterday morning near or just after sunrise and we expect that to happen again today.

Once we get past the chilly kickstart to Monday, temperatures warm into the 50s and low 60s across the Bay Area and into the mid 50s to mid 60s for the Central Coast.

LONG TERM

Issued at 126 AM PST Mon Dec 29 2025 (Tuesday through Sunday)

Cluster analysis in addition to the EPS and GEFS shows upper level ridging holding through Tuesday, leading to another quiet day. Guidance than clearly depicts ridging building over the Intermountain West. Over the Pacific, a cutoff trough deepens and gradually lifts north, transitioning more to an open wave feature. To the west of that, troughing over the Gulf of Alaska deepens and gradually advances westward. Wet weather looks to begin Wednesday, with periodic bouts of rain holding through the weekend. Both systems look to tap into tropical moisture, with IVTs projected to be around 250 kg/(ms). Given last week's storm systems, nuisance flooding for poor drainage and urban areas will be possible, as well rises on flashy creeks/streams. Given the nice weather over the next two days, now is a good time to check storm drains and gutters to make sure they're not clogged. The WPC has highlighted Santa Lucia Range and Sierra de Salinas in a Marginal Risk for excessive rainfall and flash flooding for Wednesday. They also placed the Bay Area and the Central Coast in a Marginal Risk for excessive rainfall and flash flooding for Friday. Given the already saturated soils and the trend in ensemble guidance and QPF cluster analysis, this appears reasonable. In addition to rain, confidence is increasing for gusty southerly winds for at least the Wednesday round of rain. Ensembles have upped the winds as we've gotten closer in time and the deterministic models continue to paint a 50kt+ jet at the 950mb level. If trends continue, a Wind Advisory may be needed.

AVIATION

(12Z TAFS) Issued at 411 AM PST Mon Dec 29 2025

Offshore winds and VFR prevail through the TAF period, with the exception of interior Sonoma county where LIFR FG is anticipated during the morning hours. Additionally, Tule fog from the Central Valley will also be creeping into extreme eastern Contra Costa county during the mornings. No other concerns elsewhere.

Vicinity of SFO...VFR. Light easterly winds under a weak offshore flow regime will persist through much of the period.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR. Light easterly winds under a weak offshore flow regime will persist through much of the period. Exception being invof the Salinas Valley (KSNS) where 10-15 kts of SE drainage flow persists.

MARINE

(Today through Saturday) Issued at 411 AM PST Mon Dec 29 2025

Gentle northerly breeze will continue today, turning more easterly by late tonight and through the middle of the week. Winds become southerly and rain chances increase late Wednesday into Thursday as the next storm system enters the waters. Seas and winds largely remain favorable throughout the week, potentially becoming hazardous by this weekend.

BEACHES

Issued at 945 AM PST Sun Dec 28 2025

Perigean spring tides (king tides) return Wednesday - Sunday. This is due to the combination of the full moon on 1/3, lunar perigee on 1/1, and perihelion on 1/3. In other words all three planetary bodies are lined up and close to each other. In addition to the high astronomical tide, the incoming low pressure system will bring strong onshore winds, generating some storm surge. The combination of these factors will bring minor coastal flooding to the low-lying areas near shorelines and tidal waterways during high tide Wednesday through Sunday. At the San Francisco tidal gauge, high tide is expected to be 1.5 ft above normal at 7:51 AM Wednesday, 1.7 ft above normal at 8:41 AM Thursday, 1.8 ft above normal at 9:34 AM Friday, 1.8 ft above normal at 10:26 AM Saturday, and 1.6 ft above normal at 11:18 AM Sunday. These predictions include 0.5 feet of storm surge that will enhance the astronomical tide and flooding threat. High tide varies up to 90 minutes earlier or later along the Pacific Coast and through the San Francisco Bay, respectively.

MTR WATCHES/WARNINGS/ADVISORIES

CA...Coastal Flood Advisory from 5 AM Wednesday to 2 PM PST Sunday for CAZ006-505-506-508-509-529-530.

Cold Weather Advisory until 9 AM PST this morning for CAZ506-510- 513>518-528.

PZ...None.