textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1202 AM PDT Tue Oct 27 2026

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

- Cool conditions through the next seven days

- Rain chances late week into early part of next week

SHORT TERM

Issued at 1202 AM PDT Tue Oct 27 2026 (Today and tonight)

Satellite imagery reveals some patchy stratus developing mainly over the higher elevations of the Bay Area and Central Coast, but also extending to a patch over Monterey Bay itself. Stratus development overnight remains somewhat uncertain but some expansion is expected through the morning hours with stratus dissipating through the late morning and early afternoon hours.

The weather pattern continues to be dominated by a large scale ridge with an axis over the Pacific Northwest, as an embedded low reinforces the larger pattern and brings the troughing influence farther south into northern and central California. Highs remain relatively cool for this time of year with middle to upper 60s expected in the interior valleys, the lower 70s in the warmest parts of extreme southern Monterey County, lower to middle 60s close to the Bays, and the upper 50s to lower 60s along the Pacific coast. Gentle to moderate onshore winds will develop this afternoon with gusts reaching 20 to 30 mph along the coast, through favored gaps and passes, and at the ridgelines.

A combination of high astronomical tides and surge from thermal expansion effects brings the risk of minor coastal flooding along the Bayshore at the San Pablo, San Francisco, and Monterey Bays, and the Pacific coast, at high tide today. At the San Francisco tidal gauge, high tide is expected to be 2.1 ft above normal (7.9 ft MLLW) at 12:15 PM Tuesday 10/27, including around 1.2 ft of surge residual partially attributed to impacts from El Nino.

LONG TERM

Issued at 1202 AM PDT Tue Oct 27 2026 (Wednesday through Monday)

Troughing will continue to impact the region through the work week. The trough pattern will get reinforced through Wednesday as a cut- off low forming over British Columbia migrates southwards, allowing a low pressure system flowing in from the central Pacific to merge into a trough axis that will extend down the West Coast and persist into the upcoming weekend. The net result will be a continued gradual cooling trend across the region with highs dipping into the middle 50s to middle 60s across the lower elevations by the latter part of the week.

For the Halloween weekend, confidence for significant rainfall has decreased since yesterday, especially across the SF Bay Area, where probabilities for rainfall have decreased to around 10-30% and measurable rainfall chances have all but vanished. The greatest chances for measurable rainfall remain around Monterey and San Benito Counties, and there rain totals are expected to be light with the probability of wetting rains (rain totals above 0.1") rather low (below 15%). Remember that last night, NBM guidance at the Monterey Airport suggested that for the 48 hour period beginning 5 AM PDT Saturday the 31st and ending 4 AM PST Monday the 2nd (note the time change, as this period includes the "fall back" from Daylight Savings Time) suggested that the 90th percentile rainfall total (a reasonable worst case scenario, with a 10% probability that the final total exceeds this value) was 1.6 inches. Now, for the same period, that 90th percentile value has dropped to 0.3 inches. It looks like the model trend is leaning more and more towards the bulk of the rainfall impacting southern California, and even there the forecast remains low confidence. An active weather pattern remains possible through the early part of next week, but any details are hard to pin down and ensemble model cluster analysis continues to depict a variable solution space that's mainly focused around how fast the troughing and ridging come through the western United States.

Coastal flooding concerns continue across Bayshore locations within the San Pablo, San Francisco, and Monterey Bays and the Pacific coastal regions through Friday. At the San Francisco tidal gauge, high tide is expected to be 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, 1.6 ft above normal (7.4 ft MLLW) at 02:39 PM Friday 10/30, and 1.0 feet above normal (6.8 ft MLLW) at 03:44 PM on Saturday 10/31, including around 1.2 ft of surge residual partially attributed to impacts from El Nino.

AVIATION

(06Z TAFS) Issued at 957 PM PDT Mon Oct 26 2026

3.2 mb ACV-SFO and 1.5 mb SFO-SAC pressure gradients support northwesterly winds, dry conditions and a few areas of low clouds /VFR-MVFR/. Cool air advection is occurring from the surface up through 850 mb (~ 5,000 feet); 925 mb and 850 mb temperatures were in the 25th percentile for late October on the evening Oakland upper air sounding. In contrast to this, sea surface temperatures in the 60s are much above October normals by 5.5F to almost 9F. Monterey bay buoy sea surface temp 67F to 68F earlier today is the warmest this late in the season for the period of record (NDBC data for Monterey buoy 1987-2023).

Back to the 00z Oakland sounding, there is a weak temperature inversion based at 5000 feet with a fair amount of vertical mixing from the surface to this altitude that'll carry over tonight over the coastal waters. Current surface weather observations are mainly VFR-MVFR. At the air/sea interface heat flow and water vapor are upward directed, with upslope winds and radiative cooling expect ongoing areas of low clouds /VFR-MVFR/ tonight and Tuesday morning. Over land where surface winds become light and there is no marine influence and temperatures cool, a few patches of valley fog /IFR- LIFR/ may develop. Otherwise it'll be VFR Tuesday.

Vicinity of SFO...VFR. West wind 10 to 12 knots tonight and Tuesday morning. West wind increasing to 15 to 25 knots Tuesday afternoon to mid evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Areas low clouds /VFR-MVFR/ tonight and Tuesday morning. Winds light and variable tonight and Tuesday morning. West to northwest winds 10 to 15 knots Tuesday afternoon and early evening.

MARINE

(Tonight through next Sunday) Issued at 848 PM PDT Mon Oct 26 2026

Moderate to fresh north to northwesterly will prevail through the majority of the week. Strong gusts will continue to develop tonight across the southern coastal waters near Point Sur and Monterey Bay. These strong gusts gradually spread across the northern coastal waters near Point Reyes by tomorrow. Isolated near gale force gusts are likely within the coastal jet regions of Point Sur and Point Reyes. In response, moderate seas briefly build to rough around 8 to 10 ft across the outer waters Tuesday afternoon into Wednesday. Moderate wind driven seas prevail Thursday into the weekend.

MTR WATCHES/WARNINGS/ADVISORIES

CA...Coastal Flood Advisory until 5 PM PDT Friday for CAZ006-505-506- 508-509-529-530.

PZ...Small Craft Advisory until 9 PM PDT this evening for Pt Arena to Pt Reyes 0-10 nm.

Small Craft Advisory until 3 AM PDT early this morning for Pigeon Pt to Pt Pinos 0-10 nm.

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

Small Craft Advisory until 9 AM PDT Wednesday for Pt Arena to Pt Reyes 10-60 NM.

Small Craft Advisory from 9 AM this morning to 9 AM PDT Wednesday for Pigeon Pt to Pt Pinos 10-60 NM.