The National Weather Service office for the San Francisco Bay Area has posted a coastal flood advisory that calls for up to 1.6 feet of water above ground level in low-lying spots along the shoreline and tidal waterways. The product was issued at 12:05 p.m. PST on Nov. 8, and for most zones it runs until 4 p.m. PST on Friday, Nov. 13. Surf on the outer coast is expected to break at 12 to 16 feet.
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The advisory text and the zones that drop off early
Not every zone shares the Friday end time. For the Coastal North Bay, Point Reyes, the San Francisco Peninsula coast and Northern Monterey Bay, the advisory lapses at noon on Tuesday, Nov. 10. A separate beach hazards statement covers the Pacific beaches through Monday evening, Nov. 9, with an elevated risk of sneaker waves and strong rip currents.
The Bay Area forecast office’s coastal flood product also builds in a storm surge allowance of up to 1.4 feet, trimmed to 1.2 feet for the Coastal North Bay. It cautions that actual high tide can arrive up to 90 minutes earlier or later along the Pacific Coast and through the Bay, so the clock times below are guides rather than guarantees.
Daily high tides at the San Francisco gauge
Forecast peaks at the San Francisco gauge are 7.3 feet above mean lower low water at 10:35 a.m. on Nov. 9 and 7.3 feet at 11:04 a.m. on Nov. 10, each about 1.5 feet above normal. Wednesday, Nov. 11 brings 7.2 feet at 11:35 a.m., Thursday, Nov. 12 brings 7.1 feet at 12:10 p.m., and Friday, Nov. 13 brings 6.9 feet at 12:49 p.m., which is 1.1 feet above normal. The late-morning timing means the peaks fall in the middle of the working day.
Those margins are small compared with the surge allowance, which is why forecasters care about what the ocean does on top of the astronomical tide. Water that sits 1.5 feet above normal needs only a modest swell to wash over a low bayshore path, a parking lot or a roadway that normally sits just above the waterline. The advisory’s wording keeps the focus on low areas next to shorelines and tidal waterways rather than on the whole urban grid.
El Niño water, a Kelvin wave and the swell outlook
U.S. Geological Survey oceanographer Sean Vitousek told the San Francisco Standard on Nov. 6 that water levels along the California coast are running about a foot above normal because of El Niño and a Kelvin wave, a subsurface wave that can lift sea level for weeks or months. In his view the biggest danger is large swells arriving at high tide, and he expects another round of big waves starting Nov. 13.
The same report quotes NWS meteorologist Joe Merchant, who said winds were expected to pick up late the following week but that it was too early to say how they would affect wave heights. Vitousek also warned that swells during the Nov. 24-26 king tides could do significant damage on the outer coast and around the bay. That later window is the actual king-tide stretch near the next full moon, which separates it from the advisory period now in force.
The Standard’s reporting also ties the water to specific places. The Embarcadero in San Francisco flooded several times in the previous week on days without rain, purely from unusually high tides, and Highway 1 near Surfers Beach, just south of Pillar Point Harbor, is exposed by erosion where waves can hit the rock seawall and spill across the road. Crews pumped sand onto that beach last spring, yet Vitousek expects similar impacts from the coming swells.
The backdrop is an ocean that has already flooded streets this season. An ABC7 report on the Oct. 26 advisory described shoreline flooding on Shoreline Highway in Mill Valley, where Battalion Chief Adam Vollmer of the Mill Valley Fire Department named the combination of tides and rain as his main concern. A KPIX account on Oct. 28 counted about 1.2 extra feet from El Niño conditions on top of a high tide running 1.9 feet above normal, which pushed San Francisco to 7.7 feet.
El Niño outlook through January-March 2027
NOAA’s Climate Prediction Center, in its Oct. 8 discussion, reports an El Niño advisory in effect with a strong-to-very-strong event likely through January-March 2027. The Bay Area office publishes its tide and wave forecasts at weather.gov/mtr, and Vitousek points readers to NOAA’s Tides and Currents service for gauge data.
The open question is how much the next swell adds. The advisory’s 1.6-foot figure assumes the forecast surge, and the 6.9-foot Friday peak is the lowest of the week. Whether the product is extended past Nov. 13 depends on the water level and waves observed in the coming days.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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