On a Tuesday in late May, the World Meteorological Organization delivered a number that concentrates the mind: there is a 90% chance that El Niño — the periodic warming of the central and eastern Pacific Ocean that reshapes weather across the entire globe — will have formed before November. Most of the climate models consulted by the WMO project the event will be "at least moderate" in strength, and several suggest it could be strong. Scientists who have studied previous cycles warn it may yet prove the most powerful this century, though the WMO's secretary general, Celeste Saulo, acknowledged that uncertainty remains considerable. "The spread is large," she said.

"There are models that are not providing any indication of a strong El Niño, while others are doing so." The stakes embedded in that uncertainty are not abstract. The most recent El Niño, which peaked in 2023–24, ranked among the five strongest on record and contributed directly to a year of record-breaking global heat. UN secretary general António Guterres warned that the coming event would "pour fuel on the fire of a warming world," with impacts that would "travel even farther and cross borders with devastating speed.

" That language was echoed by the WMO's own forecast, which projected unusually high temperatures across nearly all regions of the planet over the next three months, alongside elevated risks of both extreme rainfall and prolonged drought. The geographical footprint of a typical El Niño is vast and contradictory. Heavier rainfall is usually recorded across parts of South America, the Horn of Africa, and central Asia, while Central America, Australia, Indonesia, and sections of south Asia tend to experience drier conditions.