In March, Nat Johnson, a meteorologist at the National Oceanic and Atmospheric Administration’s (NOAA) Geophysical Fluid Dynamics Laboratory, noticed a striking signal emerging from his Earth system model. The model—built to forecast El Niño, the climate pattern driven by unusually warm waters in the eastern tropical Pacific Ocean—was projecting what appeared to be the second-strongest event since 1991.
“Only 1997 was comparable,” Johnson says, referring to the El Niño that triggered droughts, floods, and widespread global weather disruption. “I knew that this was something unusual.”
What once looked like an outlier forecast is now becoming the consensus view. In NOAA’s latest outlook released today, the agency confirmed that El Niño conditions have already formed, as warm waters continue moving eastward toward the typically colder waters off the coast of Peru. The report estimates a 63% chance that this event will develop into a very strong El Niño later this year—nearly twice the probability given in May.
If these projections hold, NOAA expects tropical Pacific sea surface temperatures could rise by as much as 2.4°C by November. That additional heat would inject energy and moisture into the atmosphere, reshaping global weather systems. Regions in the southern United States, eastern Africa, and China could see heavier rainfall and flooding, while Indonesia, Australia, and southern Africa may face heightened drought and wildfire risk. The Pacific hurricane season could intensify, while activity in the Atlantic may weaken. El Niño conditions also tend to elevate global average temperatures, increasing the possibility that 2027 could become a record-hot year.
Forecasts of El Niño had been anticipated for months, but the level of confidence in its potential strength is new.
“There’s personal confidence, and then there’s numerical confidence,” says Emily Becker, an atmospheric scientist at the University of Miami and member of NOAA’s El Niño forecasting team.
NOAA’s outlook combines model simulations based on ocean and atmospheric observations with expert interpretation. While earlier models this century often overestimated El Niño strength, Becker says the current convergence of predictions is unusual.
“We did not have probabilities anything like this,” she notes.
Forecasters became more confident after passing what scientists call the “spring predictability barrier.” During spring, unpredictable wind bursts can either strengthen or weaken developing El Niño conditions. These bursts are often triggered by transient weather systems such as tropical cyclones and thunderstorms, making long-range prediction extremely difficult.
“We would be needing to predict these pulses of winds months in advance to get that [El Niño] amplitude prediction right,” says Sarah Larson, an atmospheric scientist at North Carolina State University. “That’s near impossible.”
This year, however, key wind events have already occurred. Reports indicate that multiple cyclones forming near Papua New Guinea helped generate strong westerly wind bursts, reinforcing warming in the Pacific.
Despite improved forecasting, tracking El Niño as it unfolds remains challenging. A global network of buoys and ocean floats measures temperature and wind conditions across the Pacific, but the ocean is vast—larger than all of Earth’s land combined.
At the same time, long-term ocean warming driven by climate change complicates detection, making it harder to separate El Niño signals from broader global trends.
To address this, scientists are increasingly using a metric called the Relative Oceanic Niño Index (RONI). Unlike traditional measures that define El Niño as a 0.5°C anomaly above a 30-year average in the tropical Pacific, RONI compares that region to the rest of the world’s oceans. NOAA has adopted this approach for the first time this year.
Even with strong confidence in the formation of El Niño, predicting its precise impacts remains difficult.
“Just having a large number for the tropical Pacific sea surface temperature mostly affects the fish,” says Michael Tippett, a climate scientist at Columbia University. “The question is: What are the impacts on the rest of the world?”
While El Niño events generally produce similar large-scale patterns, their local effects vary significantly. According to Wilfran Moufouma-Okia of the World Meteorological Organization, warming global conditions may further amplify extremes.
“In a warming climate, the atmosphere is primed with more moisture and energy,” he explains, increasing the potential severity of associated weather events.
Nat Johnson also warns that overlapping climate pressures could worsen outcomes in vulnerable regions.
He highlights coral reefs and fisheries already stressed by marine heatwaves, as well as ecosystems like the Amazon, which are experiencing prolonged drought conditions.
“I’m particularly concerned about areas where the El Niño impacts and the long-term trends may reinforce each other,” Johnson says.
One of the most striking aspects of the current situation is the speed of the transition. The planet was still in a La Niña phase in early 2025, characterized by cooler-than-average Pacific waters. The shift to a potentially strong El Niño has occurred unusually quickly.
“This is an unusual forecast,” says Becker. “But unusual only goes back about 75 years.”
Scientists note that while it is not yet clear how much climate change influences the rapid swing, some models suggest that more extreme transitions between El Niño and La Niña may become more common in a warming world.
Despite uncertainties in regional outcomes, researchers emphasize that the overall signal is clear: significant global weather disruptions are likely.
“When the models are that confident,” Johnson says, “I don’t dismiss that.”
As the event develops, scientists will continue refining forecasts, but they caution that the world should already be preparing for a potentially powerful El Niño—and the widespread impacts it may bring.
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