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    "original_url": "https:\/\/www.nytimes.com\/2026\/09\/30\/climate\/el-nino-storm-flooding-kelvin-waves.html?emc=edit_na_20261001&nl=breaking-news&segment_id=227364",
    "parsed_content": "AdvertisementSKIP ADVERTISEMENTSupported bySKIP ADVERTISEMENTA Kelvin Wave Is Heading Toward the California Coast, Bringing TroubleAn enormous pulse of wave energy will soon reach Southern California and continue north, raising sea levels by half a foot and increasing threats from swells and tides.Share full articleA wave crashes into a sea wall protecting beachfront homes in Long Beach, Ca., where a boardwalk was damaged by Hurricane Marie.Credit...Mario Tama\/Getty ImagesBy Raymond ZhongSept. 30, 2026Leer en espa\u00f1olSee more of our coverage in your search results.Encuentra m\u00e1s de nuestra cobertura en los resultados de b\u00fasqueda. Add The New York Times on GoogleAgrega The New York Times en Google In the coming days, sea levels off Southern California are expected to begin rising by half a foot or more and then stay elevated for months, as an enormous pulse of wave energy generated by El Ni\u00f1o travels up the coast, lifting the water as it goes.\n \n \n \n \nWeek ending Aug. 28\n+4\n+8\n+12\n+16\nin.\nAbove average sea surface height\nUNITED STATES\nSan Francisco\nLos Angeles\nSan Diego\nHouston\nMEXICO\nLa Paz\nPuerto Vallarta\nAcapulco\nPacific\nOcean\nWeek ending Aug. 28\n+4\n+8\n+12\n+16\nin.\nAbove average sea surface height\nUNITED STATES\nSan Francisco\nLos Angeles\nSan Diego\nHouston\nMEXICO\nLa Paz\nPuerto Vallarta\nAcapulco\n \nWeek ending Sept. 18\n+4\n+8\n+12\n+16\nin.\nAbove average sea surface height\nUNITED STATES\nSan Francisco\nLos Angeles\nSan Diego\nHouston\nMEXICO\nLa Paz\nPuerto Vallarta\nAcapulco\nPacific\nOcean\nWeek ending Sept. 18\n+4\n+8\n+12\n+16\nin.\nAbove average sea surface height\nUNITED STATES\nSan Francisco\nLos Angeles\nSan Diego\nHouston\nMEXICO\nLa Paz\nPuerto Vallarta\nAcapulco\n \nWeek ending Oct. 8 (forecast)\n+4\n+8\n+12\n+16\nin.\nAbove average sea surface height\nUNITED STATES\nSan Francisco\nLos Angeles\nSan Diego\nHouston\nMEXICO\nLa Paz\nPuerto Vallarta\nAcapulco\nPacific\nOcean\nWeek ending Oct. 8 (forecast)\n+4\n+8\n+12\n+16\nin.\nAbove average sea surface height\nUNITED STATES\nSan Francisco\nLos Angeles\nSan Diego\nHouston\nMEXICO\nLa Paz\nPuerto Vallarta\nAcapulco\n Note: Weekly average sea surface height anomaly compared to a 1993-2025 baseline. Source: Analysis of Copernicus GLORYS data by Dillon Amaya, North Carolina State University. Mira Rojanasakul\/The New York Times \n \n \u201cIt\u2019s one of the first, if not the first indication that El Ni\u00f1o is here,\u201d said Dillon Amaya, an assistant professor in the department of marine, earth and atmospheric sciences at North Carolina State University.This pulse, known as a Kelvin wave, will boost the ocean\u2019s height across an area extending 12 to 18 miles offshore. It is coming on top of several other factors that are raising the seas off California and increasing the threats from coastal flooding, erosion and saltwater intrusion.AdvertisementSKIP ADVERTISEMENTSea levels have already been abnormally high for months because of how warm the Pacific has been. Warm water occupies more volume than cool water does, and that\u2019s one way human-caused climate change is raising the ocean\u2019s height globally.By unlucky coincidence, the tidal cycle off California will also be peaking in the coming months. And ocean swells are likely to be amped up this fall and winter by El Ni\u00f1o-fueled storms. (Hurricane Polo, one of the most intense hurricanes ever recorded in the eastern Pacific, made landfall on Tuesday in Mexico.)\u201cFor us in California, really what causes overtopping and flooding are when waves arrive at high tide,\u201d said Mark Merrifield, director of the Center for Climate Change Impacts and Adaptation at the Scripps Institution of Oceanography in La Jolla, Calif.With so many elements stacking on top of one another to increase ocean heights, it\u2019s \u201chighly probable\u201d that California will soon witness its highest sea levels ever recorded, Dr. Merrifield said.Last week, Gov. Gavin Newsom, a Democrat, declared a state of emergency to prepare the state for El Ni\u00f1o. He directed agencies to position equipment like sandbags and pumps and to help local communities to prepare for coastal floods and landslides. The California National Guard has also been told to prepare for search and rescue efforts.AdvertisementSKIP ADVERTISEMENTEl Ni\u00f1o, the naturally recurring phenomenon in the Pacific, is starting to deliver a host of weather hazards across the planet, dumping extra rain in some regions and drying out others. This year\u2019s El Ni\u00f1o is predicted to be the strongest on record, meaning its influence on temperatures, rainfall and storms could be especially stark.For California, the boost to sea levels began nearly half a world away.Normally, the trade winds blow from east to west over the tropical Pacific, pushing sun-warmed water toward Asia and holding it there. So deep is this bulge of balmy water that the ocean is typically about a meter higher off Indonesia than it is off Ecuador.But during El Ni\u00f1o conditions, the trade winds are disrupted and weakened. The pileup of warm water in the western Pacific starts spilling eastward, toward the Americas, in what oceanographers call Kelvin waves. The name comes from Lord Kelvin, the 19th-century British physicist who first described such waves. (You might also know his name from the unit of temperature that bears it: the kelvin.)These aren\u2019t waves like the ones you\u2019d see on a shoreline, cresting and crashing every few seconds. They aren\u2019t tsunamis, either. Think instead of a vast, rolling procession of water, affecting the seas at depths of up to 650 feet.\u201cIt\u2019s thousands of square kilometers of water sloshing back all at once,\u201d said Dr. Amaya, who tracks El Ni\u00f1o\u2019s influence on sea levels. \u201cThere\u2019s a lot of potential energy there.\u201dAdvertisementSKIP ADVERTISEMENTBursts of wind can give the water an extra kick. That\u2019s what happened in August: A two- to three-week-long series of stiff westerly winds out in the middle of the Pacific sent a strong Kelvin wave heaving east until it reached Peru and Ecuador around Sept. 1.Blocked by the land of South America from continuing eastward, the energy in this wave has traveled along the coasts instead, one pulse heading north and another south. Earth\u2019s rotation has kept the pulses pinned up against the shore. The northbound one crawled up the western coasts of Central America and Mexico and is expected to reach San Diego in early October, by Dr. Amaya\u2019s calculations.Left alone, this pulse would dampen over one to three months as it continued toward Alaska. But, as El Ni\u00f1o gains strength, further bursts of westerly wind could kick up three or four more such pulses that keep the ocean elevated through early next year, Dr. Amaya said.Besides increasing threats onshore, the pulse of warm water could expose marine ecosystems to greater heat stress. It can also suppress the rise of cold, nutrient-rich water from the ocean depths. With these cold waters limited to smaller areas along the coasts, whales could wander closer to land in search of food, increasing the risk of deadly ship strikes and beaching.From the commentsMira RojanasakulClimate graphics editorSea levels off California have already been elevated because of the unusually warm water, and they\u2019re about to see another boost from El Ni\u00f1o-related disturbances and storms. Big waves have already caused damaged in some areas, like Long Beach. What else are readers in California seeing and experiencing?AdvertisementSKIP ADVERTISEMENT",
    "published_at": "2026-09-30T09:01:37+00:00",
    "author_name": "Raymond Zhong",
    "site_name": "The New York Times",
    "section": "Climate",
    "publisher": "The New York Times Company",
    "ai_headline": "A Kelvin Wave Is Heading Toward the California Coast, Bringing Trouble",
    "ai_simplified_title": "Kelvin Wave Heads to California Coast, Raising Sea Levels",
    "ai_excerpt": "An enormous Kelvin wave, generated by El Ni\u00f1o, is expected to raise sea levels off Southern California by half a foot or more, increasing threats of coastal flooding and erosion. This comes as other factors, including warm Pacific waters and peak tidal cycles, also contribute to higher ocean levels.",
    "ai_subject_tags": [
        "El Ni\u00f1o",
        "Kelvin Wave",
        "Sea Level Rise",
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