NOAA Officially Declares El Niño, Raises Super El Niño Probability to 63%

Timeline and Confidence Through Winter

The CPC's projections leave little ambiguity about the event's staying power. El Niño has a 96% probability of continuing through the December 2026–February 2027 period . The agency reports essentially 100% odds of El Niño persisting through the fall, reflecting unusually high confidence driven by the massive volume of subsurface oceanic heat and the consistent expansion of westerly wind anomalies across the equatorial Pacific .

Experimental seasonal forecasts from NOAA's Geophysical Fluid Dynamics Laboratory echo this high confidence, showing an elevated likelihood of a moderate-to-strong El Niño by fall, with continued strengthening through early winter . The International Research Institute at Columbia University assigns a 97–98% probability of El Niño through early 2027 .

The Subsurface Engine: How a Kelvin Wave Is Driving This El Niño

Beneath the surface, the physical driver of this rapid warming is a massive, eastward-moving pulse of anomalously warm water known as a downwelling Kelvin wave. This subsurface feature stretches thousands of kilometers across the equatorial Pacific and reaches depths of roughly 600 to 1,000 feet . Originating in the western Pacific warm pool, the wave transports an immense reservoir of heat toward South America, where it is now upwelling to the surface and directly fueling the observed spike in sea surface temperatures.

The Japan Meteorological Agency's latest analysis confirms that subsurface water temperatures are above normal across the entire equatorial region, particularly in the central and eastern Pacific, and that the eastward propagation of this warm water is expected to continue at least through boreal autumn . The speed and scale of this heat transfer is what gives forecasters high confidence that surface warming will not only persist but intensify into the coming months.

A Super El Niño on a Warmed Planet

The 2026 event is not developing in isolation. It is amplifying an already warm global climate system. Each of the seven years from 2019 through 2025 featured large marine heatwaves, and a massive marine heatwave has dominated waters off the U.S. West Coast since it reached maximum intensity in September 2025 . NOAA Fisheries scientists noted that this is only the third time in records that such a large coastal ocean area has remained this warm for this long without the presence of an El Niño .

Because an El Niño event transfers vast quantities of heat from the ocean into the atmosphere, scientists widely expect 2027—not 2026—to eclipse 2024 as the warmest year on record, given the typical lag time for the full global temperature signal to emerge . In April 2026, NOAA reported that 29% of the global ocean was experiencing marine heatwave conditions, and that figure is forecast to rise to roughly 40% by September—driven in part by the developing El Niño .

What a Strong El Niño Has Historically Meant for Southern California

For the southern United States and particularly Southern California, a strong El Niño winter historically tips the odds toward wetter and cooler than average conditions. This pattern is driven by a more active subtropical jet stream that carries moisture-laden storms across the Pacific and into the region. California also typically experiences more frequent and intense atmospheric river events during strong El Niños, although the exact placement of the heaviest rainfall and potential flooding is hard to predict far in advance . NOAA has also noted that the combination of El Niño-driven ocean warming and already-elevated sea levels could amplify high-tide flooding impacts along parts of the U.S. coast this winter .

International Preparations and Early Warnings

The World Meteorological Organization (WMO) has been consistently signaling the likelihood of this event. In April 2026, the organization stated there was "high confidence in the onset of El Niño, followed by further intensification" . WMO chief of climate prediction Wilfran Moufouma Okia emphasized the need for early preparations, noting that El Niño would layer further global temperature increases and heightened extreme weather risks on top of the underlying human-caused warming trend .

The available reporting did not include a specific June 2026 statement from U.N. Secretary‑General António Guterres tied to this declaration, though Guterres has previously and consistently called for universal early warning system coverage and disaster preparedness in the context of El Niño-amplified climate risks. The formal shift to an El Niño Advisory by NOAA reinforces those same calls to readiness across affected regions.