El Niño has returned, and U.S. National Oceanic and Atmospheric Administration forecasts now put the odds of a “super El Niño” at more than 60% by the end of 2026. The article says such an event in the equatorial Pacific could make 2026 one of the hottest years on record, possibly the hottest ever, with effects already being felt in places such as Western Europe through more extreme weather, unusually high temperatures, greater wildfire risk, and pressure on the economy and water supplies.
The announcement that El Niño had officially developed came on June 11, after sea-surface temperatures in the central and eastern equatorial Pacific stayed at least 0.5 degrees Celsius above average for several consecutive months. NASA scientists also saw a companion sign of the phenomenon, higher sea levels in parts of the Pacific, which reflect warm water expanding as it heats. The data came from the Sentinel-6 Michael Freilich satellite, launched in 2020 by NASA and the European Space Agency and processed by NASA’s Jet Propulsion Laboratory.
The satellite picked up early warning signals when warm Kelvin waves, hundreds of kilometers wide, moved eastward across the Pacific. Those waves form as trade winds weaken, allowing warm water to pile up in the east, deepen the warm layer, and reduce the upwelling that normally keeps the Pacific coasts of the Americas cooler. Sea-level measurements can detect heat stored below the surface, which is important because subsurface warmth can shape weather and climate even more than surface readings.
NASA Jet Propulsion Laboratory sea-level researcher Dr. Severine Fournier said conditions in the western Pacific on June 8 resembled those seen in 1997, when a very strong El Niño developed, though the eastern Pacific was still lagging behind then. She said more warm Kelvin waves appear to be heading east, and that “it looks like it is going toward large, record-breaking heat waves, with a higher probability than I would have said last week,” but added that more observations are needed. A super El Niño would mean tropical Pacific sea-surface temperatures rising by more than 2 degrees Celsius, releasing more ocean heat and potentially pushing global temperatures to unprecedented levels on top of human-driven warming.
