This Kelvin wave originated at the equator this summer before reaching California earlier this month. Its energy pushed the thermocline\u00a0– the transition zone between warm surface water and cold water below\u00a0– hundreds of feet deeper. That makes winds, waves and currents less effective at mixing cooler, nutrient-rich water to the surface.<\/p>\n
“All the changes we are seeing right now caused by El Ni\u00f1o are stacking on top of (an) existing marine heat wave,” which began in 2025<\/a>, said Daniel Rudnick, a professor of physical oceanography at UC San Diego, at a recent university panel<\/a>.<\/p>\n The changes are literally stacking up.<\/p>\n As water warms, it takes up more space, a phenomenon known as thermal expansion. Tides are running more than a foot above normal along much of the California coast. San Francisco already set an October high tide record<\/a>, and is expected to surpass it next week.<\/p>\n Worse is in store. Historically high tides are expected during the weeks of Thanksgiving and Christmas. If a storm coincides with those high points, it could create a “perfect storm<\/a>” that could severely impact Bay Area homes and transportation routes.<\/p>\n The climate model of the European Center for Medium Range Weather Forecasts\u00a0predicts sea surface temperatures will average 10 degrees above normal along much of the California coast from November through January. Tides will continue to run exceptionally high until El\u00a0Ni\u00f1o wanes in spring or summer.<\/p>\n Intense downpours and tornadoes<\/p>\n Coastal California is expected to see more thunderstorms than usual this winter as elevated ocean temperatures juice up the lower atmosphere. Similarly warm seas during the 1998 El Ni\u00f1o increased energy for coastal thunderstorms by about 26%, scientists found.<\/p>\n More thunderstorm energy increases the potential for waterspouts and tornadoes. During a very strong El Ni\u00f1o in 1983, a tornado damaged more than 100 homes in Los Angeles.<\/p>\n El Ni\u00f1o-warmed waters, along with human-caused climate change, also supercharge atmospheric rivers<\/a>.<\/p>\n “If you have 20 to 40 atmospheric rivers in a winter and each one is 1% to 2% wetter, that translates to a lot of extra water coming down on land,” John O’Brien, a climate scientist and a program officer for science at the Heising-Simons Foundation, previously told the Chronicle<\/a>.<\/p>\n Kelp forests and sea birds dying, rare fish sightings<\/p>\n Kelp forests off the Southern California coast are dying due to unusual ocean heat all the way to the sea floor, said Jennifer Smith, a professor of marine biology at UC San Diego.<\/p>\n “For those of you who are scuba divers, you’ve probably noted that even on the bottom, at 50 feet, it is 70 degrees \u2026 it’s been very, very warm,” Smith said at an Oct. 7 panel<\/a>. “When kelp is exposed to that warm water for extended periods of time, it literally melts.”<\/p>\n The Scripps Pier (San Diego) underwater camera showed visibility exceeding 30 feet on Monday, which “rarely gets this good,” according to UC San Diego. (UC San Diego\/Scripps Institution of Oceanography)<\/p>\n This nutrient-depleated water warm is also less rich in oxygen, critical for microscopic creatures like plankton. Fewer plankton result in clearer water\u00a0– like in La Jolla on Monday, when underwater visibility exceeded 50 feet\u00a0– but sends seabirds scrambling for a source of food. Hundreds of seabirds are dying from starvation along the Northern California coast, according to the nonprofit International Bird Rescue<\/a>.<\/p>\n The unusual heat is drawing tropical fish close to the state’s shore.<\/p>\n Giant oceanic manta rays have been spotted near San Diego, a “very rare” sighting, according to Andy Leising, a research oceanographer at the National Oceanic Atmospheric Administration.<\/p>\n Striped Marlin are being caught far north of their typical habitat and more mahi mahi, bluefin tuna and bonito are being caught close to shore.<\/p>\n An olive ridley sea turtle, normally found in tropical waters, was discovered laying eggs in Southern California in September, the first time<\/a> in history a sea turtle was documented nesting on the U.S. West Coast.<\/p>\n “We’ll keep seeing unusual things all winter!” Leising said.<\/p>\n Subscribe<\/p>\n There’s more to San Francisco with the Chronicle. Subscribe today for just 25\u00a2.<\/a><\/p>\n![\"The](\"https:\/\/www.newsbeep.com\/us-ca\/wp-content\/uploads\/2026\/10\/https:\/\/media.zenfs.com\/en\/san_francisco_chronicle_hearst_178\/3fbecddeb7b47cc2b264f1f056a0ebe8.jpg\"\/)
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