“Super El Niño” might already undersell it. “I would suggest maybe we need a new category of extreme El Niño,” said Dr. Daniel Swain, a climate scientist with the University of California Agriculture and Natural Resources and a research affiliate at the NSF National Center for Atmospheric Research. “The forecast for this year is genuinely extreme. It greatly exceeds even very strong events that we’ve seen historically.”
Swain offered that assessment during American Community Media’s weekly news briefing on Aug. 21, where moderator Sandy Close opened by citing a recent New York Times headline declaring El Niño “back, and worse than ever.” Swain pointed to a red blob of ocean data sprawled across the tropical Pacific, a forecast he had plotted the day before for the November-through-January window. “This actually is more textbook than the textbooks that we actually have available to us today,” he said.
What the numbers actually show
El Niño is a natural cycle in which the normally cool waters off Peru and Ecuador warm for months at a stretch, shifting storm tracks as far away as California, Indonesia, and Europe. “El Niño equals warmer-than-average eastern tropical Pacific Ocean,” Swain said. “That’s what it is in a nutshell.”
There is no formal definition for a “super” El Niño — it’s shorthand for a very strong event, and this year strains even that label. Sea surface temperatures in the eastern tropical Pacific are already the warmest ever recorded for this time of year, and they warmed faster this spring and summer than in any comparable stretch on record. Swain expects the event to peak between October and December, with the worst impacts outside the tropics landing between December and March.
One misconception needs correcting before winter arrives, he warned. “El Niño doesn’t guarantee a wet winter in California,” Swain said, “but a very strong, potentially historically strong event — which is again our expectation for this year — likely increases the amount of precipitation that California will experience this winter.” In other words: more rain is likely, not certain. And the flood risk that comes with it, coastal and inland, is real either way.
Where California will feel it first
The coast will feel it soonest. Ocean temperatures off central and southern California are climbing, pulling subtropical fish into waters where they don’t belong and making late-summer heat waves more dangerous, since humid air makes it harder for the body to cool itself through sweat. Sea levels will rise next, and the timing is unlucky: the same November-December window brings both winter storms and the year’s highest natural tides, the so-called king tides.
Swain pointed to his own hometown of San Rafael, in Marin County, as one of many flood-vulnerable Bay Area communities where apartment buildings already flood during ordinary storms. He flagged the Pacific Coast Highway near Malibu, eroding from above and below, and the Amtrak line connecting Los Angeles and San Diego, closed since early erosion began. “It’s going to be difficult to safely reopen that this year,” he said.
Los Angeles is already responding. “You can go right now to some of the beaches in the coastal areas,” Swain said. “You can watch bulldozers building these giant sand berms to protect against the expected increase in sea level and in wave activity.” Asked whether the coming season should be treated as a strategic threat requiring an immediate surge in disaster resources, Swain was measured. “This is not an imminent disaster,” he said. “It’s also not a guaranteed disaster.” What the region has, he said, is time: “We actually have a good opportunity, a fairly long runway in front of us before most of the negative impacts might materialize, and so that gives us some real time to potentially do something about it.”
Does a wetter winter mean a bigger Sierra Nevada snowpack? “It depends,” Swain said. Warmer storms can deliver plenty of precipitation as rain instead of snow. “We could have a wet, warm winter,” heavy snow at the highest elevations, but comparatively little at resorts like Lake Tahoe.
A trillion-dollar question for the Southwest
What would a super El Niño mean for a Southwest that’s already two decades into drought, following the federal government’s recent cuts to Colorado River allotments? “I would say this is the million-dollar question,” Swain said, “but it’s probably closer to a trillion-dollar question, given the stakes at hand.”
His answer carried a warning wrapped inside good news. The lower Colorado basin, including Arizona, will likely see an average or above-average winter. But that relief won’t fix the underlying math. “The scope of the water loss in the Colorado River basin is now so extreme that even perhaps the wettest year on record would not solve the problem,” Swain said, pointing to long-term aridification and demand that already outstrips supply before climate change even enters the equation. A good winter buys time. It doesn’t change direction.
The health risks nobody asks about first
Floods and droughts tied to El Niño could drive up bacterial illnesses such as Cyclospora, and Swain cautioned that waterborne disease risk rises most in communities with fragile water infrastructure, including some rural and tribal communities in the Southwest.
But he raised an unexpected concern of his own: valley fever, a soil-borne fungus that thrives in Arizona, California, and northern Mexico after wet stretches give way to dry, windy ones. “There’s already some alarm bells potentially ringing about valley fever and soil-borne fungal pathogens,” he said, “because these are more widespread.” Farmworkers and incarcerated people, who often lack access to filtered air, face the highest exposure.
What can be done
Two pieces of advice stood out. The first was financial. Most Americans in flood-risk zones carry no flood insurance, Swain said, in part because it doesn’t come bundled with a standard policy. “People are very exposed, maybe more so to flood risk than to other natural hazards in the U.S., in terms of their financial exposure,” he said, calling this “a great year” to look into coverage: “I think it actually is a very smart investment.”
The second was aimed squarely at journalists. Swain has watched exaggerated headlines about extreme weather trigger a backlash in which scientists overcorrect and understate real risk. “Please really think carefully about the headlines,” he said, “because that is ultimately the thing that gets the clicks, as we all know on the internet, and it’s the thing that sometimes it’s the only thing that some people will ever read.”
El Niño itself cannot be stopped; it’s the planet’s own pressure valve, releasing stored ocean heat back into the atmosphere. What can be controlled is what happens next. “We can’t prevent El Niño,” Swain said, “but we can slow and then halt climate change, and for things like El Niño we can prepare, hopefully successfully, to mitigate its impacts by putting measures into place to make those impacts less consequential.”
