El Niño is expected to intensify into a very strong event before the end of the year, a sharp escalation from forecasts three months ago that mostly pointed to moderate strength, raising the risks of drought, floods and extreme heat into 2027.
The World Meteorological Organization said on Thursday there is a nearly 100% likelihood that El Niño will persist through February 2027, the first time one of its El Niño/La Niña updates has expressed such a high level of certainty.
In June, WMO put the probability of El Niño developing between June and August at 80% and said most forecasting models indicated a moderate event, although some suggested it could become strong.
The phenomenon is now firmly established and expected to strengthen further, fueled by exceptionally warm surface and subsurface waters across the tropical Pacific. WMO expects it to reach very strong intensity before peaking toward the end of the year, with climate effects continuing well into 2027.
WMO officials said at a press conference in Geneva that the event could rank at the high end of El Niño events observed using comparable monitoring methods over the past four decades, although its eventual peak remains uncertain.
“This exceptional El Niño demands exceptional preparation and response,” WMO Secretary-General Celeste Saulo said.
“Never before in the 50-year history of the World Meteorological Organization have we launched such a major mobilization with National Meteorological and Hydrological Services who are on the frontline of delivering the forecasts and services to save lives and livelihoods,” she said.
The shift since June is visible in measurements across the Pacific. The Niño 3.4 index, a widely used measure of sea-surface temperature anomalies in the central-eastern equatorial Pacific, averaged 1.5° Celsius above normal from May through July and reached 2° above normal in July.
Weekly readings subsequently rose to approximately 2.2° to 2.6° above average between late July and mid-August, indicating continued intensification. Below the surface, the heat is more pronounced. Subsurface ocean temperatures in some areas were more than 8° above average during July and early August, according to WMO.
“The sea surface warming, the subsurface ocean heat content, and the atmospheric circulation are singing the same song,” Wilfran Moufouma Okia, WMO’s chief of climate prediction, told reporters.
Under WMO’s classification, an El Niño is considered very strong when the relevant sea-surface temperature anomaly exceeds 2°. Moufouma Okia said forecasting models currently produce an average peak of around 3.6°, although individual models range above and below that figure and the eventual magnitude will only be known when the event peaks.
“El Niño is being supersized before our eyes,” U.N. Secretary-General António Guterres said. “The science leaves no room for doubt: the planet is in uncharted waters, and those waters are heating up.”
El Niño is a naturally occurring climate pattern and is not caused by climate change. Saulo said there is no established link between climate change and the frequency or strength of El Niño, but the event is adding heat to an already warming climate.
The powerful 2023-24 El Niño contributed to 2024 becoming the warmest year on record. “We should not be surprised if this record is broken,” Saulo said.
A very strong El Niño increases the likelihood of significant changes in rainfall and temperatures, but WMO cautioned that its intensity does not determine the severity of impacts in individual countries.
Moufouma Okia said El Niño changes the probability of particular climate conditions but does not predict individual disasters. “It is not a forecast of storm or a forecast of heat wave,” he said.
Its effects vary by location and season and interact with other climate systems. A positive Indian Ocean Dipole is also forecast to develop this fall, while tropical Atlantic waters are expected to remain warmer than normal, conditions that could reinforce, weaken or alter typical El Niño effects in different regions.
For September through November, its multi-model forecasts indicate an increased likelihood of above-normal temperatures across almost all land areas, while projected rainfall shows a pronounced atmospheric response associated with the strong Pacific El Niño.
WMO also sees increased chances of wetter-than-normal conditions across much of Africa and parts of South America, while drier-than-normal conditions are favored across the Indian subcontinent, Southeast Asia, Australia, northern South America, Central America and the Caribbean.
Governments are already acting. Panama has declared a national state of emergency to mobilize preventive spending, while the Panama Canal Authority has introduced water-saving measures. India has convened an interministerial preparedness review covering agriculture, health, water, power and the economy, while Pacific countries are preparing for an above-average tropical cyclone season.
The consequences could also persist after El Niño itself begins to weaken. Saulo said the event is expected to push global average temperatures higher and that knock-on effects on agriculture, hydropower and water availability could continue into 2027 and 2028 in some countries.
“El Niño does not have to be a recipe for disaster,” Saulo said. “We have the forecast, the foresight to save lives and protect livelihoods.”
