WMO says this El Niño may run off the 40-year chart and last into 2027

The World Meteorological Organization said on 3 September that the present El Niño is likely to last through at least February 2027 and may become the strongest event since the agency’s four-decade monitoring record began. WMO Secretary-General Celeste Saulo told reporters in Geneva that if the current path holds, the episode will sit “off the charts we have used for the past four decades.” The agency put the chance of persistence through February at nearly 100 percent.

United Nations Secretary-General António Guterres used a shorter phrase. “El Niño is being supersized before our eyes,” he said. “The planet is in uncharted waters, and those waters are heating up. The world is in the danger zone of extreme weather.”

The physical marker is sea-surface temperature in the central and eastern equatorial Pacific. The Niño 3.4 index averaged about 1.5C above normal from May to July. Weekly values from late July to mid-August ran from about 2.2C to 2.6C above the baseline. Temperatures below the surface have run more than 8C above average in places. Models compiled by WMO and by independent groups put the peak near 4C in November. The previous satellite-era high anomaly was about 3.1C in 2015.

Zeke Hausfather, writing in July once the full set of seasonal model runs was in, put the multi-model median peak at 3.6C on a detrended Niño 3.4 series, against a prior record of 2.75C in 2015–16. About 91 percent of ensemble members beat that record. The gap between this forecast median and the old record is larger than the gap between the strongest and the fifth-strongest events of the past 150 years.

A separate United Nations assessment issued this week warned that the world is likely to cross 1.5C of long-term warming in the next few years. El Niño does not create that baseline. It adds a pulse on top of it. Because heat takes time to move through the ocean and the atmosphere, 2027 is expected to be hotter than 2026 even after the Pacific event peaks.

The World Food Programme has projected that this event could push an additional 49 million people into hunger. The pattern is familiar and still costly: drought risk in parts of southern Africa, Central America and the western Pacific; flood and landslide risk on the west coast of South America; a hotter, wetter winter signal for parts of the southern United States; and extra fuel for fire weather where dry seasons coincide with the extra heat.

Indonesia is already in that cycle. Weeks of peat and forest fires on Sumatra and Borneo have closed classrooms for 1.43 million pupils. Pontianak recorded an air-quality index of 1,023. Those fires are seasonal. A record El Niño makes the dry season longer and the peat easier to light.

Daniel Swain of the University of California Agriculture and Natural Resources said the event will be so large that “I’m not sure we fully understand” the consequences. That is a fair description of the forecast plume. The numbers that are not in dispute are the ones already on the buoy network: 2.2C to 2.6C in the weekly Niño 3.4 series, subsurface heat well above the 2015 analogue, and a WMO statement that treats a February 2027 end date as the base case rather than a tail risk.