People walk during a storm near Sausalito, Calif., on Feb. 5, 2024.
People walk during a storm near Sausalito, Calif., on Feb. 5, 2024.
All eyes are on the unusual power of this year’s El Niño.
A monthly outlook the Climate Prediction Center published on Thursday gives a 69% chance that El Niño will become “historic” this fall, exceeding the strength of all previous events on record since 1950.
Since January, forecasts have become increasingly confident in the intensity of this El Niño, a climate pattern that will primarily drive winter weather in California and across the globe.
“This is a genuinely remarkable event,” Daniel Swain, a climate scientist for the University of California’s Agriculture and Natural Resources group, said during an online briefing Monday. “... The numbers I’m seeing — the numbers that other climate and weather folks are seeing — are frankly pretty extraordinary. If they come to pass, they will blow all historical events out of the water in terms of El Niño intensity.”
The National Oceanic and Atmospheric Administration’s Climate Prediction Center included this image in its outlook on Aug. 13, 2026, showing the current sea surface temperatures in the Pacific Ocean.
The National Oceanic and Atmospheric Administration’s Climate Prediction Center included this image in its outlook on Aug. 13, 2026, showing the current sea surface temperatures in the Pacific Ocean.
El Niño is the warm phase of a seasonal pattern that develops along the equator in the Pacific Ocean. During El Niño, weak winds are associated with above-average water temperatures. Year to year, these natural events alternate irregularly with the opposite phase, La Niña, and neutral ocean conditions.
El Niño emerged in June. By July, the Climate Prediction Center reported an 81% chance that El Niño would rank as “very strong” from October through December. Thursday’s report raised those odds.
“El Niño is strengthening, with a greater than 90% chance of a very strong event during the Northern Hemisphere fall and winter 2026-27,” the latest memo stated. “... With an event of this magnitude, the chances of experiencing impacts consistent with El Niño are larger, but they are not guaranteed.”
Since 1950, only a handful of El Niño events have fallen into the “very strong” category, which the National Weather Service measures as temperatures in certain areas of the tropical Pacific Ocean that reach greater than 2 degrees Celsius above normal. El Niño conditions in the winter of 1982 to 1983 ranked as the strongest on record, at a peak near 2.5 degrees Celsius. The winters of 1991 to 1992, 1997 to 1998 and 2015 to 2016 were among those that had similar, though slightly lower, temperatures.
According to the latest numbers from the Climate Prediction Center, temperature anomalies in the Pacific have yet to reach such high levels. But its models show the heat increasing significantly as the year progresses and potentially cresting above previous El Niño events. Some projections suggest this event will get warmer than 3 degrees Celsius.
This is an Aug. 3, 2026, image from the Sentinel-6 Michael Freilich satellite, which uses radar altimetry to collect sea surface height data.
This is an Aug. 3, 2026, image from the Sentinel-6 Michael Freilich satellite, which uses radar altimetry to collect sea surface height data.
“It’s here, and it’s big,” Josh Willis, a senior research scientist for NASA’s Jet Propulsion Laboratory, told SFGATE. “There’s been a lot of consternation over how big is it? Is it going to be the biggest? And my answer is that it’s big enough. Whenever there’s one of this magnitude, we see big impacts. We already see big impacts in the tropics, and they’ll move out of the tropics as we get closer to the new year.”
Californians are especially concerned with what El Niño means for the state’s winter rain and snow. El Niño tips the odds in favor of a wetter season, especially in the southern part of the state.
But El Niño’s influence is also global. “El Niño is a natural pattern, but it’s happening an unnaturally warming world,” Alexander Gershunov, a research meteorologist at the Scripps Institution of Oceanography at UC San Diego, told SFGATE. “And the most direct consequence of that is that we’re going to break the world temperature record this year.”
Other impacts include the fact that the eastern Pacific hurricane season, already off to a roaring start, can intensify during El Niño years. And scientists are already seeing evidence of the expected and temporary rise in the height of the seas in the eastern Pacific, since El Niño’s warmer water expands in volume. Various oceanic forces will push these taller waters from coastal South America north toward California later this year.
Swain emphasized that the triple threat of climate change, the influence of El Niño and this December’s king tides could bring unprecedented sea levels, and therefore coastal flooding, to California. He sees big problems ahead for Highway 1 and Highway 101.
A view of flooding as heavy rain hits the San Francisco Bay Area on Nov. 13, 2025.
A view of flooding as heavy rain hits the San Francisco Bay Area on Nov. 13, 2025.
“Coastal flooding is going to be a big, big risk this winter,” Swain said. “And not just along the oceanic coast, but also the coasts of all of California’s coastally connected bays and estuaries. So that does include the San Francisco Bay Area, Monterey Bay area and, frankly, parts of the interior of Northern California.”
Although Swain considers this outcome “almost certainly going to happen,” the effect of El Niño on rain is less certain. The winter of 2015-2016, the infamous “Godzilla” El Niño — one of the strongest ever recorded — did not deliver the expected precipitation in Southern California. Even so, the seemingly endless string of rainy days from past El Niño winters such as 1997-1998 loom large in the collective memory of residents.
Yet even that winter, since the rain fell across many days, was not the costliest flood year, according to Jan Null, a meteorologist and private weather consultant with Golden Gate Weather Services. In fact, he reports that out of the most expensive flood years since 1950, just five were during El Niños, while four were during La Niñas and three were during neutral years.
“In terms of California precipitation, I would think it will be an above-normal year,” Null told SFGATE. “But will it be 10% above normal or 50% above normal? And what about the distribution of that rain?”
To alert residents of the upcoming El Niño, California state Sen. Mike McGuire hosted a virtual town hall on Aug. 4 that included Swain, representatives from Scripps and the California Governor’s Office of Emergency Services. It had wide public attendance.
Now is the time to prepare, according to Patrick Barnard, who directs research at the Center for Coastal Climate Resilience at UC Santa Cruz.
“We don’t know where we’re going to get intense rainfall, but we do know that virtually every coastal community in California is going to see higher sea levels and larger waves this winter — plus a series of very large wave events that are going to put a lot of stresses on our coastal infrastructure and our communities,” Barnard told SFGATE.
“This is about as sure a thing as you can get, in terms of the predictive capabilities of NOAA and other experts across the country and the world,” he added. “This is going to be a significant event.”
Aug 13, 2026