Bay Area Sea Levels Expected To Rise Nearly 1 Foot Due To "Planetary Wave"

CBS Bay Area

September 8, 2026

A slow-moving wave is travelling up the North American coast and is expected to raise water levels in the Bay Area by nearly a foot next month. But it's not going to be one giant crashing wave; in fact, people may not even notice it if they head to the coast.

The swell moving up the coast is a planetary-scale process, meaning it's thousands of miles wide, known as a Kelvin wave, and is a direct impact of El Niño. During an El Niño event, winds shift and draw warmer ocean water from offshore and pushes it towards Central America. When the warmer water slams into the coast, it sends a coastally trapped wave, also known as a Kelvin wave, up the West Coast and towards Alaska, which can take months at a time.

But again, it won't be one giant wave that you can see crashing at the beach. The wave is currently moving north across Central America's coast at around 6 mph. It's expected to arrive to Baja in the next week or so, Southern California by late September/early October, and the Bay Area by the first or second week of October.

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