A Kelvin wave linked to El Niño is heading toward California, potentially raising Bay Area sea levels by up to a foot this fall, which could increase the risk of coastal flooding. This large-scale ocean phenomenon, expected to reach the coast by October, causes a rise in sea levels of 6 to 12 inches without noticeable changes for beachgoers.
Dillon Amaya, a marine science professor, explains that Kelvin waves form when trade winds weaken, allowing warm water in the Pacific to push back towards South America, and then travel north along the U.S. West Coast. The added sea level rise poses flooding risks, especially during king tides and storms, prompting cities like Sausalito to take precautionary measures, including allocating funds for infrastructure improvements.
Bay Area sea levels are already six inches above normal, and Amaya predicts that several more Kelvin waves could arrive this fall and winter, maintaining elevated water levels until at least spring 2027. This phenomenon highlights how invisible ocean changes can significantly affect coastal infrastructure and flood-prone areas.
