San Francisco Bay hit its highest October tide on record Saturday, and the water reached places it normally only touches during big winter storms, the San Francisco Chronicle reported.
The reading at the San Francisco gauge topped the previous October mark of 1.4 feet above the normal daily tide, which was set only last year. It also came in more than 0.2 feet above what the National Weather Service had forecast. Before the weekend, the weather service had predicted a peak of 7.3 feet above mean lower low water at 11:50 a.m. Saturday, a figure that already counted up to 1.2 feet of surge on top of the astronomical tide.
Roads under water in Mill Valley
The California Highway Patrol shut the northbound Highway 101 off-ramp in Mill Valley around 12:25 p.m., according to the Chronicle. Incident logs showed at least one vehicle was trapped after a driver went into the water, and a nearby park-and-ride lot flooded.
Mill Valley police also asked drivers to stay off Miller Avenue between Camino Alto and Almonte Boulevard starting about 12:30 p.m. The road was still closed in both directions around 2:30 p.m., with no reopening estimate, according to Bay City News via SFGATE.
On the ocean side, waves pushed water at the south end of Ocean Beach close to the dunes near Sloat Boulevard.
Why October, and why now
October usually brings some of the mildest tides of the year because of how the moon and sun line up. The Chronicle tied the unusual height to El Niño, which is driving record-warm sea surface temperatures off California. Warmer water expands and takes up more room, lifting tides. This year already set records in June and July.
Scientists expect El Niño to bring record king tides to the coast and the bay this winter. In the last very strong El Niño, in 2015-16, parts of Ocean Beach eroded by as much as 180 feet, the U.S. Geological Survey found.
More high water through Tuesday
A coastal flood advisory for low-lying bay shoreline runs through 3 p.m. Tuesday, Oct. 13, the Southern Marin Ledger reported. The weather service forecast high tides of about 7.3 feet around 12:18 p.m. Sunday, 7.1 feet around 12:46 p.m. Monday and 7.0 feet around 1:14 p.m. Tuesday at the San Francisco gauge, with timing varying by up to 90 minutes around the bay. Forecasters warned of flooded lots, parks, trails and roads, plus sneaker waves and rip currents at the beach.
The advice is simple: give yourself extra travel time, respect barricades and never drive into water when you can't tell how deep it is.