Sonoma, CA Weather

: New SHORT TERM, LONG TERM:

Key messages

Updated at 107 PM PDT Thu Oct 29 2026

- Moderate coastal flooding at high tide for Bayshore and Pacific Coast locations through Friday; coastal flooding continues for Bayshore locations on Saturday

- Seasonal to slightly below normal temperatures through the extended forecast

- Potential for rain this weekend

Short term

Issued at 107 PM PDT Thu Oct 29 2026 (This evening through Friday night)

A deep upper level trough originating from the Gulf of Alaska will continue to move into the West Coast through the weekend. It will bring an influx of colder air that continues to keep our temperatures below normal through the extended forecast. Did you feel a chill in the air this morning? North Bay residents saw the coolest temperatures with lows dropping into the upper 30s/low 40s across the interior Valleys. Expect cooler morning conditions to continue Thursday night into Friday morning as highs drop in the 40s across the North Bay and low to mid 50s across the rest of the Bay Area and Central Coast. High temperatures on Friday will be in the 60s across the region with upper 50s to low 60s directly along the coast.

High resolution guidance does show some potential for light rain tonight into Friday but confidence is on the lower end. KMUX continues to show some light radar echoes in the Central Coast with nothing across the Bay Area. If we were to see showers they would be most likely over the Central Coast, where the best moisture currently is, while the Bay Area stays dry. Another factor to consider is where in the atmosphere the moisture is. Model guidance suggests the primary moisture source is high level which means any showers that do develop today will be high based. Which means, given the large dry lair precipitation must fall through to reach the surface, it is likely that any falling precipitation will evaporate before reaching the ground (virga). While noticeable rain is unlikely, we can expect to see a return of low level clouds overnight as additional low level moisture begins to arrive with the more unsettled weather.

The Coastal Flood Advisory continues Thursday and Friday with up to 1.9 ft of inundation above ground level expected today (10/29) within +/- 90 minutes of high tide (1:43 PM). Tidal heights are expected to trend downwards through the remainder of the week with up to 1.6 ft of inundation above ground level possible on 10/30 with high tide occuring at 2:39 PM. The caveat to this is that tidal anomalies have not been decreasing as rapidly as initially thought that they would which necessitated the advisory being expanded into Friday and Saturday. So although the current advisory expires on Saturday, there is still the potential for the advisory to be expanded into Sunday if the anomaly continues to trend downwards slower than anticipated.&&

Long term

Issued at 107 PM PDT Thu Oct 29 2026 (Saturday through next Wednesday)

Upper level troughing will become more pronounced across the West Coast Saturday and Sunday. Guidance shows a few areas of weak low pressure developing offshore of the PNW and offshore of Northern California. A slightly stronger area of low pressure is located to the southwest of Southern California and will strengthen into a weak low pressure system as it moves towards the California-Mexico border. This system is associated with a much more impressive moisture transport that will move into Southern California with the tail edge of the moisture just tapping the Central Coast and Bay Area. The current forecast shows minimal rain across our forecast area with only a few hundredths of an inch expected. The exception would be the North Bay Coastal Mountains and the interior Central Coast where between a tenth to a quarter of an inch is expected. For the North Bay Coastal Mountains, orographic uplift is likely responsible for the slightly higher totals. The Interior Central Coast benefits both from orographic uplift along the Gabilan range and from being closer to the primary moisture plume over Southern California. The previous shift noted that precipitation values for this weekend have been flipping around which is still partially true. Up until this morning's forecast update, the values had been trending downwards. However, models are now keying in on the moisture plume spreading more northwards and ensembles show the potential for a trace of rain to a tenth of an inch. This is consistent with the current forecast and there is good consensus between the ECMWF and GFS that precipitation will be light. Showers are likely to develop early Saturday morning across the interior Central Coast and spread northwards into the Bay Area by late Saturday. Light rain/drizzle may start during prime Trick or Treating hours but the highest chances for precipitation will fall after midnight/early Sunday morning. There is a low (< 15%) chance of thunderstorms on Saturday/Sunday as this system moves through. The overall environment looks fairly marginal but the upper level low is transporting a cold enough airmass in that it may be enough to bring localized thunderstorms to the higher elevations. The best potential is over the marine environment and along the coastline with much lower chances across the interior.

Below normal temperatures continue this weekend into next week as the upper level trough brings another round of much colder air into the region. The 850 mb temperature looks to drop to between 4-6 C this weekend which is below the 25% percentile of 850 mb temperatures for late October. As a result, high temperatures will be well below average on Saturday in the upper 50s to low 60s. We can expect temperatures to gradually warm up heading into next week as the trough moves out and upper level ridging rebuilds across the region. This would see temperatures warming back into the upper 60s to low 70s across the interior while coastal areas stay in the upper 50s to 60s. The most recent forecast update has pushed our next rain episode back from mid next week to late next week. Ridging is now expected to persist through the first part of the week with the next trough not set to arrive until Wednesday/Thursday. It's too far out to talk about rain totals for this event but it will definitely be something to keep an eye on.

Coastal flooding concerns continue across Bayshore locations within the San Pablo, San Francisco, and Monterey Bays through Saturday. At the San Francisco tidal gauge, high tide is expected to be 1.1 feet above normal (6.9 ft MLLW) at 03:44 PM on Saturday 10/31.

Aviation

(18Z TAFS) Issued at 1044 AM PDT Thu Oct 29 2026

High clouds continue to stream overhead with ceilings between 15kft and 25kft and will likely lower to around 10kft late this evening and into Friday morning. Onshore winds will increase once again by late morning and especially so by this afternoon and into the early evening. Winds diminish overnight and into Friday morning. Onshore winds increase once again by Friday afternoon.

Vicinity of SFO: VFR through the TAF period. Onshore winds increase by early afternoon and persist through the late evening before diminishing and become light/variable Friday morning. There is less than a 20% probability for MVFR ceilings to develop across the Bay Area terminals early Friday morning.

SFO Bridge Approach: Similar to SFO.

Monterey Bay Terminals: VFR through the TAF period. Onshore winds return later this morning and prevail through sunset this evening. KSNS is currently experiencing (southeasterly) drainage winds that are forecast to return onshore by early afternoon. There is a 15-30% probability for MVFR ceilings to develop late this evening and into Friday morning, yet the lack of a marine layer and high cloud cover is forecast to limit this potential.

Marine

(Today through Tuesday) Issued at 1044 AM PDT Thu Oct 29 2026

Conditions gradually improve through the day with strong northwest breezes becoming fresh to moderate with rough seas improving as well. Improving conditions will continue into the weekend while a long period west-northwest swell arrives this weekend and continues into next week.

Watches, warnings and advisories

CA: Coastal Flood Advisory until 6 PM PDT Saturday for CAZ006-506- 508-529-530.

Coastal Flood Advisory until 5 PM PDT Friday for CAZ505-509.

PZ: Small Craft Advisory until 3 PM PDT this afternoon for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.