El Niño, UN: peak in December, could be one of the strongest since 1950
The phenomenon is intensifying and will continue until February 2027. Sea surface temperatures in the central-eastern Pacific will reach record levels between October, November and December 2026
El Niño is set to continue intensifying over the coming months. The climatic phenomenon, which periodically causes abnormal warming of the surface waters of the central and eastern Pacific Ocean, could peak in December, and there is a probability of nearly 100 per cent that it will persist until February 2027. The alarm has been raised by the World Meteorological Organisation (WMO) of the United Nations in its monthly update on the global seasonal climate. WMO Secretary-General Celeste Saulo warns that this could be one of the most intense events recorded since at least 1950.
Rising temperatures
According to the WMO, surface water temperatures in the central and eastern tropical Pacific will reach record levels between October, November and December 2026, influencing global weather patterns with repercussions for economies, ecosystems and communities around the world.
It is likely, in fact, that El Niño – which occurs every two to seven years and lasts between nine and twelve months – will bring above-average temperatures to much of the planet and alter rainfall patterns, increasing the risk of droughts and floods in various regions.
“El Niño is now fully established and is rapidly intensifying,” announced Saulo, explaining that this phenomenon “does not add new heat to the planet, but releases the heat that the ocean had already stored beneath the surface. This is why a high-intensity event often coincides with one of the hottest years on record, as happened in 2024. The ocean from which this heat originates is the warmest we have ever measured: there is simply more heat available to be released.”
The waters of the Pacific
Anomalies in the sea surface temperature of the central-eastern equatorial Pacific are measured using the Niño 3.4 index, which shows a significant increase: it rose from an average of +1.6 degrees above normal in June 2026 – the month in which the US National Weather Service announced the return of the phenomenon – to +2.5 degrees in August of the same year. For the October–November–December quarter, however, the average seasonal sea surface temperature anomaly is forecast to reach around +3.7 degrees, peaking, as mentioned, around December. The WMO explains that this would be the highest value ever recorded since observations began, exceeding the previous record of +2.6 degrees recorded between November 2015 and January 2016.
