Southern California is known for its sunny beaches, kelp forests, and cool, nutrient-rich Pacific waters. But right now, a powerful climate pattern called El Niño is dramatically changing the ocean along the West Coast.
During El Niño, changes in ocean circulation and winds can weaken the upwelling that normally brings cold, nutrient-rich water toward the surface along the West Coast. One part of this process is a Kelvin wave—a pulse of warm water that travels eastward along the equator before helping push warmer-than-usual water north along the California coast. As a result, ocean temperatures can rise, currents can shift, weather changes, and marine life can be disrupted.
Here are a few of the ways El Niño can transform Southern California’s ocean and the wildlife that calls it home.
Tropical animals head north
Whale sharks, giant manta rays, and hammerhead sharks are all usually found in warm tropical and subtropical waters. But during strong El Niño conditions, warm water can push northward along the California coast, bringing these enormous animals with it. And they’re not the only ones. Eastern Tropical Pacific orcas were also recently spotted in Southern California, a surprise since these mammals usually don’t venture north of Mexico.
NOAA has identified these species as tropical visitors that can make northerly appearances during warm-water events – and it’s not the first time. During the strong 2015-2016 El Niño, some of these animals also were among the suite of tropical species appearing unusually far north.
These sightings are spectacular, they are also a reminder of changing ocean conditions. When temperature and prey availability shift, marine predators and other animals may change where they travel, feed, and spend time.
Sea turtles nest in California for the first time
In September 2026, two olive ridley sea turtles laid eggs on Southern California beaches for the first time in history.
In the Pacific, olive ridley sea turtles typically nest farther south, from the coast of Mexico to Panama. They can occasionally be spotted in Southern California, but nesting here had never been documented before.
Some scientists say this year’s strong El Niño may be the reason these olive ridleys traveled farther north. But sea turtles also rely on a variety of factors to navigate the ocean besides water temperature, so it’s possible that this new development is also connected to food availability or other water conditions.
Yellow-bellied sea snakes wash ashore
One of the strangest El Niño visitors is the yellow-bellied sea snake.
These highly venomous sea snakes normally live in tropical and subtropical waters, with their range extending north only as far as the tip of Baja California. But during El Niño, unusual currents can carry them much farther north.
Only a few yellow-bellied sea snakes have ever been collected in California, with nearly all sightings occurring during El Niño years. The first documented California sea snake was found during the 1972–73 El Niño, while several more appeared during the powerful 2015–16 event.
Their appearances are a dramatic example of how changing currents can transport animals far beyond their normal ranges.
Local wildlife suffers
While El Niño can bring unusual tropical species into Southern California, it can also make life much harder for animals that normally call these waters home. Under normal conditions along California’s coast, cold, nutrient-rich water rises from the deep ocean, fueling tiny organisms like plankton, which form the foundation of the marine food web. When El Niño weakens this process, fewer nutrients reach the sunlit surface and that can mean less food for animals all the way up the food chain.
Animals like California sea lions are forced to turn from eating sardines and anchovies – nutrient-rich foods – to snacking on lower quality prey, and they have to travel further to get it. For moms and pups, this can leave pups waiting longer between meals and struggling to gain weight.
Seabirds can face similar challenges. Without their usual prey, seabird species like pelicans and cormorants struggle to fill their bellies, which can lead to declines in breeding attempts and success, as well as slower growth rates for chicks.
A warmer ocean can mean a very different ocean
A sea turtle nesting on a Southern California beach or a whale shark swimming off the coast may seem like isolated incidents. But together, these sightings tell a bigger story: the ocean is currently changing, and wildlife is responding.
El Niño is a natural climate pattern, but as our climate continues to change, so do these patterns. As oceans warm overall, they can add more energy to El Niño patterns, potentially making extreme weather events even more intense or creating a “Super El Niño.”
As El Niño develops, scientists are watching Southern California’s waters closely to see what other unexpected visitors turn up and what those arrivals can teach us about a changing ocean.
