UN Warns El Niño peak December May Break Pacific Heat Records

The El Niño peak December forecast has the world's meteorologists watching the Pacific Ocean more closely than at any point in a decade. The World Meteorological Organization said this week that the naturally occurring climate phenomenon will keep strengthening ahead of the El Niño peak December maximum, potentially ranking among the most powerful such events since at least 1950. According to the agency's monthly Global Seasonal Climate Update, released on October 9, the warming of the central and eastern tropical Pacific will drive weather patterns with consequences for economies, ecosystems, and communities across the globe.

The forecast in numbers

The El Niño peak December forecast is built on the Niño 3.4 index, the standard measure of sea-surface temperature anomalies across the central-eastern equatorial Pacific, which rose from an average of 1.6 degrees Celsius above normal in June to 2.5 degrees above normal in August. For the October-to-December season the anomaly is forecast to reach approximately 3.7 degrees above normal, peaking around December. If that forecast materializes, it would be the highest value since observations began, well above the previous record of 2.6 degrees set during the 2015-to-2016 event. Separately, Japan's weather bureau said the September sea-surface temperature anomaly in its El Niño monitoring region reached 4.0 degrees Celsius, the highest since records began in 1949, and expects the conditions to continue into the Northern Hemisphere winter.

Why forecasters sound so sure

The projection rests on a consensus among thirteen national and international meteorological centres, from Washington to Tokyo to London to Pune, pooling real-time readings from ocean buoys, satellites, and radiosondes coordinated by the WMO. The models give the El Niño peak December event a near-100 per cent chance of persisting through February 2027. "El Niño is firmly established and strengthening rapidly," said WMO Secretary-General Celeste Saulo, as reported by AFP. Saulo added that El Niño does not create new planetary heat; it releases warmth the ocean has stored below the surface, and the ocean it is drawing from is the warmest ever measured.

What El Niño actually does

El Niño occurs when sea-surface temperatures rise across the central and eastern equatorial Pacific, reshuffling global wind patterns, atmospheric pressure, and rainfall. It recurs roughly every two to seven years and typically lasts between nine and twelve months. Strong events often produce the hottest calendar years on record in the year after they peak, which is why scientists are watching whether the recent record warmth was a preview rather than a peak.

Where the weather shifts

In the months running up to the El Niño peak December maximum, the update predicts an overwhelming likelihood of above-average temperatures across large parts of the planet. Rainfall patterns are expected to shift in a way forecasters call classic for a strong El Niño. Wetter-than-normal conditions are more likely over the Greater Horn of Africa, southeastern South America, parts of North America, and the central and eastern equatorial Pacific. Drier-than-normal conditions are forecast for the Indian subcontinent, southern Central America and parts of the Caribbean, and northwestern South America. The WMO notes these seasonal signals describe where unusual conditions are more likely, and they do not replace national and local forecasts.

The impacts are already starting

Some places are already feeling the strain of the El Niño peak December event. According to AFP, severe drought is hitting parts of Central America, where crops are dying and livestock are at risk. Researchers at the University of Chicago's Climate Impact Lab estimated the event could drive as many as 451,000 excess heat-related deaths worldwide, Reuters reported. The WMO warns the shifting rainfall could raise the risk of both drought and floods in different regions, threatening farms, water supplies, and food security hardest where reserves are thinnest. The event is unfolding against a warmer baseline than ever before: the last strong El Niño helped make 2023 the second-warmest year on record and 2024 the hottest, with global temperatures reaching roughly 1.55 degrees above the 1850-to-1900 pre-industrial average. This year, global sea-surface temperature hit an all-time observed high in August, the hottest August on record according to Copernicus, NOAA, and NASA, the same summer half of Europe faced record heat stress.

What happens next

Alongside El Niño, other drivers shape the seasonal outlook. A positive Indian Ocean Dipole, a pattern that strongly influences rainfall around the Indian Ocean, is expected to peak in October and then fade, while sea-surface temperatures in the equatorial Atlantic are forecast to stay above normal. Meanwhile the WMO says national weather services and regional climate outlook forums are stepping up briefings for decision-makers and humanitarian partners, with recurring updates to support preparedness on water management and public health, especially for those most vulnerable to extreme heat. The extreme heat tied to the El Niño peak December maximum is also a headline theme at the Global Heat Forum under way in Bangkok, where scientists and officials are meeting to turn climate science into practical protection as the December peak approaches.