NOAA releases new sky-high odds of historic El Niño in California

After emerging in June, El Niño is now gathering power in the Pacific Ocean.

A new outlook released on Thursday shows an 81% chance that El Niño, the climate pattern that generally brings a wet winter to California along with a cascade of global weather impacts, will rank as “very strong” from October through December.

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The forecast, a monthly memo from the National Weather Service’s Climate Prediction Center, also expects that El Niño conditions will linger through early spring 2027. The new report expressed more confidence than June’s that the event will ultimately fall into the strongest of four categories.

“I cannot recall a time in my career where the model guidance has been so consistently predicting a strong-to-very strong El Nino,” Michelle L’Heureux, who leads the ENSO team at the Climate Prediction Center, wrote to SFGATE. She added, “This still means there is a 1-in-5 chance of the event being less than very strong, but these are still impressive probabilities for ENSO forecasts made in early July.” 

El Niño is the warm phase of a pattern that develops in the tropical Pacific Ocean, called the El Niño-Southern Oscillation, or ENSO. During El Niño events, weak trade winds are associated with above-average surface temperatures in those waters. The other phase, La Niña, brings stronger winds that promote cooler ocean conditions. The pattern alternates irregularly, with neutral phases in between.

This year’s El Niño drives up the chances of extreme weather events like heat waves, drought and heavy rainfall in many parts of the globe, the World Meteorological Organization recently reported.

“The WMO community has launched an unprecedented mobilization to coordinate activities across the United Nations and at regional level to support governments, humanitarian organizations and climate-sensitive sectors,” WMO Secretary-General Celeste Saulo said in a recent statement. “Advanced seasonal forecasts and early warnings are vital to save lives and cushion the impact on our economies and our communities.”

In California, the El Niño pattern tips the odds in favor of a wetter winter season, especially in the southern part of the state. Eastern Pacific hurricane activity can also intensify. Additional impacts might also include a temporary rise in sea levels, coastal flooding and erosion, agricultural crop damage and, combined with the extreme marine heat wave already baking the Pacific Ocean, severe disruptions to marine life. California’s skiers and snowboarders can expect increased chances of a higher snowpack in the Sierra Nevada, according to NOAA. 

Uncertainty remains, however, over how exactly El Niño will take shape in California. First, some models show this El Niño developing into the same range as the seven “very strong” events since 1950, while others forecast it could be the strongest ever. Josh Willis, a senior research scientist for NASA’s Jet Propulsion Laboratory, told SFGATE that the event got a slow start compared with previous notable El Niños based on sea level metrics.  

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“I would call this El Niño a late bloomer,” Willis said. “A lot of people predicted a really huge El Niño, and it could still be, but right now it’s smaller than 2015 was in July, and it’s way smaller than 1997 was in July. So where’s it going to land in this biggest category? I would say it’s unlikely to be the strongest El Niño in 30 years, but it’ll wind up being pretty strong.”

Even in the case of a super potent El Niño, certain impacts are not an exact science. Stronger events — meaning warmer seas along the equator — can tilt chances in favor of expected outcomes, but they don’t always pan out as anticipated, according to the recent outlook. 

Regarding rainfall in California, for example, scientists have to come to appreciate that El Niño years can lead to a variety of outcomes. The seemingly endless string of rainy days from past El Niño winters such as 1997-1998 loom large in the collective memory of residents. But in 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.

“This [outlook] bumps it up into the higher odds of being in the very strong category,” Jan Null, a meteorologist and private weather consultant with Golden Gate Weather Services, told SFGATE. He added: “But we still don’t know what the impacts are going to be from that, and that’s the screaming message that I like to get out.”