The year's highest tides are coming, and forecasters say this could be the winter when they bite. The California Coastal Commission lists this season's king tides as Nov. 24 to 26, Dec. 23 to 25 and Jan. 21 to 22, with some Northern California spots also peaking Dec. 22, Jan. 20 or Jan. 23.

The biggest one is predicted for Dec. 24 at 10:37 a.m., when NOAA's tide tables call for 7.23 feet at the San Francisco gauge and about 7.9 feet at Alameda. Every king tide this season peaks in the morning.

Why this year is different

The Coastal Commission says scientists expect a historically strong El Niño plus Kelvin waves, slow bulges of warm water that temporarily raise sea level. That means actual tides can run higher than the printed predictions. If a storm arrives during a king tide, CBS San Francisco reports, 3 feet or more of flooding above normal is possible.

Where the water goes first

A Bay Conservation and Development Commission study, summarized by CBS San Francisco, maps what happens as total water levels climb:

  • 1 foot: San Rafael (Highway 101, I-580, the SMART train, the Bay Trail), Corte Madera and Larkspur, including the Larkspur Ferry Terminal, and Martinez.
  • 2 feet: Marin City, Suisun City, south Richmond, downtown and West Oakland around Jack London Square and the Port of Oakland, parts of San Jose near Highway 237, and Redwood City.
  • 3 feet: Napa, East Oakland near the Coliseum, BART and Oakland Airport, Alameda, Mountain View's North Bayshore, East Palo Alto and San Francisco's Bayview-Hunters Point.
  • 4 feet: San Francisco's Mission Bay and Embarcadero, where flooding near the Ferry Building could cut off about 7,000 daily ferry riders and reroute five Muni bus lines.

The study treats 4 feet as a long-range scenario that becomes routine between 2060 and 2120, so this winter is a preview more than a forecast.

What you can do

If you live or commute through those low spots, check the tide time for your shoreline before heading out on king tide mornings and watch for storm forecasts in those windows. The Coastal Commission's King Tides Project also invites residents to photograph the high water and upload it to its public map.