American Canyon, CA Weather

Key Messages

Updated at 1207 AM PDT Sun Oct 25 2026

- Seasonably warm conditions today

- Cool conditions through the next week

- Rain chances late week into the upcoming weekend

- Minor coastal flooding at high tide for Bayshore locations through the week

Short Term

Issued at 1207 AM PDT Sun Oct 25 2026 (Today and tonight)

Satellite imagery reveals mostly clear skies across the region save for a patch of stratus that has developed near Bodega Bay and Dillon Beach and a little bit eastward through the Petaluma Gap. Skies should remain mostly clear through the next day, barring any radiational stratus and fog that develops within the North Bay early in the morning, which should dissipate after sunrise.

A warm period continues across the region as a shortwave ridge sandwiched between a departing low moving into the Desert Southwest and an developing one off the coast of British Columbia and the Pacific Northwest. Highs remain seasonably warm with highs in the lower to middle 70s expected across the inland valleys, highs in the upper 70s across the warmest spots of the southern Salinas Valley and the Morgan Hill-Gilroy area, the upper 60s to lower 70s close to the Bays, and the upper 50s to middle 60s along the Pacific coast. A gentle onshore breeze should develop in the afternoon, with gusts to 20 mph possible within the Salinas Valley.

A combination of high astronomical tides and surge from thermal expansion effects brings the risk of minor coastal flooding across Bayshore locations within the San Pablo Bay, San Francisco Bay, and Monterey Bay at high tide today. At the San Francisco tidal gauge, high tide is expected to be 1.5 ft above normal (7.3 ft MLLW) at 11:07 AM Sunday 10/25, including around 1.0 ft of surge residual partially attributed to impacts from El Nino.

Long Term

Issued at 1207 AM PDT Sun Oct 25 2026 (Monday through Saturday)

Large-scale troughing persists across the Western US as a low moves across the Pacific Northwest, and by the middle of the week, a second developing low over British Columbia will interact with a decaying low moving in from the central Pacific to reinforce the troughing. Some light sprinkles are possible in the northern coastal waters and the adjacent areas of the North Bay on Monday morning as the low passes by, but most of the impacts will be felt along the North Coast and across Oregon. Otherwise, highs will start to dip for the work week, with highs in the inland valleys dropping to the middle to upper 60s by Monday and the lower to middle 60s for the second half of the week.

The end of the week into the upcoming weekend is where things get interesting in terms of the forecast, for it is where the model outputs start to diverge and the resulting uncertainty ratchets upward. Comparing mean outputs from two of the global ensemble models reveals a remarkably different solution across the Western United States. The European ECMWF ensemble model mean suggests that the trough will continue handing on through the upcoming weekend while the American GEFS ensemble model mean depicts a slight ridge coming in and breaking up the trough's influence by next Sunday, the first day of November. Ensemble model cluster analysis for Day 7 (Saturday) reinforces this split between a more trough-influenced solution from the European ensemble members, and a more ridge- influenced solution from the American ensemble members, with the members of the Canadian GEPS ensemble model split between the two with a slight lean towards the American ensemble solution. As a side note, this whole discussion may illuminate why model output around and beyond 200 hours is generally considered unreliable by those. The current forecast shows rain chances coming in Friday into the upcoming weekend, but with the split between the models that's pretty much all that can be said with even a moderate degree of confidence. We will keep a close eye on the forecast, not least because it could determine whether people need to consider ponchos or umbrellas as part of their Halloween plans.

Coastal flooding concerns continue across Bayshore locations within the San Pablo, San Francisco, and Monterey Bays through the next week, and will expand into the Pacific coastal regions by Monday through Friday. At the San Francisco tidal gauge, high tide is expected to be 1.6 ft above normal (7.4 ft MLLW) at 11:39 AM Monday 10/26, 1.8 ft above normal (7.6 ft MLLW) at 12:15 PM Tuesday 10/27, 1.9 ft above normal (7.7 ft MLLW) at 12:56 PM Wednesday 10/28, 1.7 ft above normal (7.5 ft MLLW) at 01:43 PM Thursday 10/29, 1.4 ft above normal (7.2 ft MLLW) at 2:39 PM on Friday 10/30, and 1.0 feet above normal (6.8 ft MLLW) at 3:44 PM on Saturday 10/31, including around 1.0 ft of surge residual partially attributed to impacts from El Nino.

Aviation

(06Z TAFS) Issued at 835 PM PDT Sat Oct 24 2026

The evening Oakland upper air sounding showed 0.43" precipitable water which is near the 10th percentile for late October. Dry air and a clear sky /VFR/ tonight to daybreak Sunday will allow radiative cooling which may form a few patches of valley fog /IFR- LIFR/ early Sunday. Cool air drainage winds i.e. land breezes will develop tonight and Sunday morning, thermally supported with land temperatures becoming cooler than sea surface temperatures (lower to mid 60s, well above October normals). Buoy air temps are cooler than sea surface temps and cooler air is forecast to continue over the coastal waters tonight, however it may be difficult for maritime low clouds to form depending if combined cooling (mainly from radiative cooling) can reach dew point temperatures. Cool air drainage breezes may help or may ultimately move low clouds away from land and mix the low clouds out. 06z TAFs continue to advertise mainly VFR.

Vicinity of SFO...VFR. West wind 10 to 15 knots decreasing to light northeasterly late tonight and Sunday morning. West wind 10 knots late Sunday afternoon and evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR. Winds east to southeast 5 to 10 knots tonight and Sunday morning. West to northwest winds 10 knots Sunday afternoon and early evening.