05/12/2026
A massive marine heat wave stretching from California to Baja Mexico is now one of the most intense ocean heat events on Earth.
Scientists say it could reshape marine ecosystems, intensify extreme weather, and linger for months.
In some regions, ocean temperatures are running more than 7°F (4°C) above average — an extraordinary anomaly for seawater.
Researchers at the Scripps Institution of Oceanography say they have been watching ocean temperature records fall repeatedly in recent weeks. At Scripps Pier in La Jolla, California, sea surface temperatures set record highs on 36 separate days between January and April alone.
What makes this event especially alarming is how deep the heat extends.
Using robotic underwater vehicles, scientists discovered unusually warm water far below the ocean’s surface — conditions more commonly associated with a major El Niño event.
But there is no full El Niño yet.
That means the Pacific could become even hotter in the coming months.
Researchers say the marine heat wave is already disrupting the ocean food chain.
Cold-water fish are moving deeper and farther north in search of cooler water, while warm-water species such as bluefin tuna and hammerhead sharks are appearing in places where they are rarely seen.
Seabirds are suffering too.
Marine researchers across California report growing numbers of starving pelicans, cormorants, and murres washing ashore emaciated because their food sources are disappearing or moving out of reach.
And the impacts may not stay offshore.
Scientists warn the unusually warm waters could intensify heat waves across the western United States, increase humidity in California, amplify rainfall events, and even make it easier for tropical systems to push farther north toward the state.
Normally, California’s cold coastal waters weaken hurricanes and tropical storms before they arrive.
This year, that natural barrier may be weaker.
Researchers say climate change is playing a major role.
Marine heat waves have become more frequent and more intense as greenhouse gas emissions continue warming the planet.
And because oceans absorb enormous amounts of Earth’s excess heat, scientists say every major marine heat wave is now starting from a warmer baseline than the last.
Learn more:
"An intense marine heat wave has California in its crosshairs, with impacts set for land and sea." CNN Weather
