El Niño heads towards its strongest level on record
The Climate Prediction Center puts the chance of a very strong event over the northern hemisphere autumn and winter at more than 90%.
El Niño has a 75% chance of becoming stronger between October and December than any event recorded since 1950, the Climate Prediction Center (CPC) has said.
The CPC, part of the US National Oceanic and Atmospheric Administration (NOAA), set out the forecast in its monthly ENSO Diagnostic Discussion on 10 September.
The 75% figure applies to the Relative Oceanic Niño Index, or RONI, which measures warming relative to the wider ocean rather than in absolute terms.
The World Meteorological Organization (WMO), in an update issued on 3 September, gave an “exceptionally high likelihood of nearly 100%” that El Niño will persist through February 2027. WMO said it was the first time one of its updates had been so unequivocal.
A very strong event can shift rainfall and temperature patterns worldwide and fuel extreme weather, WMO said, with the risks of floods, drought and extreme heat running well into 2027.
Strength alone does not decide how severe those effects are in any one country, WMO cautioned. They vary by location and season, and can be modified by other climate drivers, including conditions in the Indian and Atlantic Oceans.
Sea surface temperatures in the eastern equatorial Pacific have already climbed more than 3°C above average, the CPC said.
The benchmark Niño 3.4 region, at the heart of the tropical Pacific, measured 1.8°C above normal in August. Further east, the Niño 3 region reached 2.5°C.
Below the surface, the CPC found widespread anomalies of more than 10°C at depth, with the thermocline deeper than average.
Winds and rainfall pointed the same way, the CPC said, with heavier rain over the central and eastern Pacific and drier conditions over Indonesia.
The WMO update tracked the Niño 3.4 index averaging 1.5°C above normal between May and July, and 2.0°C in July alone.
Weekly values climbed further, to between 2.2°C and 2.6°C above average from late July to mid-August, which WMO said pointed to continued intensification.
“El Niño is being supersized before our eyes. The science leaves no room for doubt: the planet is in uncharted waters, and those waters are heating up,” said UN Secretary-General António Guterres.
WMO Secretary-General Celeste Saulo said the event demands “exceptional preparation and response,” adding that the organisation has never mobilised national meteorological and hydrological services on this scale in its 76-year history.
El Niño is a natural warming of the ocean surface in the central and eastern equatorial Pacific, one phase of the El Niño–Southern Oscillation, or ENSO, and occurs every two to seven years.
It typically peaks between November and February, WMO said, and is not caused by climate change.
The CPC’s next monthly assessment is due on 8 October 2026.