After months of anticipation, the National Oceanic and Atmospheric Administration (NOAA) officially declared the onset of El Niño today. It could become one of the strongest El Niño events in history.
According to the agency, there is now a 63% chance of El Niño intensifying to “very strong” status between November and January, potentially ranking among the largest events in the historical record going back to 1950. Extreme climate and weather impacts are more likely to occur during stronger El Niños. Over the past several weeks, meteorologists have warned that this event could lead to record-shattering temperatures, supercharged storms, regional droughts, wildfires, or floods, and global food shortages.
A so-called “super” El Niño would also have major implications for the climate crisis. “Starting soon all months will be the warmest on record once El Niño kicks into high gear,” Jeff Berardelli, chief meteorologist and climate specialist for WFLA Tampa Bay, posted on X yesterday. “Biggest impacts on global temp will be later this year into next year. It will set a new precedent… for a couple of years… until it’s broken again.”
Hello, El Niño
El Niño is the warm phase of the El Niño/Southern Oscillation (ENSO), a periodic fluctuation in sea surface temperature and air pressure over the equatorial Pacific Ocean. ENSO is the biggest, most influential year-to-year climate variation on the planet, so both El Niño and its cold-phase counterpart, La Niña, have significant consequences for global temperatures and weather patterns.
NOAA is the second major weather agency to declare El Niño after the Japanese Meteorological Agency made the call on Wednesday. Other countries and the United Nations’ World Meteorological Organization are sure to follow. NOAA made its determination based on persistent above-average sea surface temperatures in the Niño-3.4 region (a key area of the equatorial Pacific used to track El Niño and La Niña) as well as wind and convection anomalies over the central and east-central equatorial Pacific.
“Collectively, the coupled ocean-atmosphere system reflected the onset of El Niño conditions,” NOAA’s El Niño advisory states.
The average of all projections by the North American Multi-Model Ensemble, a seasonal forecast system that combines multiple climate models running across the U.S. and Canada, shows that El Niño will intensify into the winter, according to NOAA.
“Even very strong El Niño events do not lead to the expected impact everywhere, but stronger events can more significantly tilt the odds in favor of expected outcomes (see CPC outlooks for probabilities of seasonal anomalies). In summary, El Niño conditions are present and expected to strengthen into the Northern Hemisphere winter 2026-27.
A Pacific warmup for the record books
Human-caused climate change will add a layer of complexity to the 2026-2027 El Niño. As carbon emissions have continued to crank up Earth’s temperature, it’s become increasingly difficult for meteorologists to separate the affects of anthropogenic warming from the natural climate variation of ENSO, meteorologist Ben Noll explains in an article for the Washington Post.
To address that problem, NOAA and other agencies now use a climate change-adjusted El Niño index called the Relative Oceanic Niño index, or RONI. According to that index, sea surface temperatures in the central equatorial Pacific during this El Niño will get an additional boost of 0.9 degrees Fahrenheit (0.5 degrees Celsius) from climate change, Noll reports.
Even without factoring in climate change, models are predicting a potentially historic Pacific warmup. According to the European Centre for Medium-Range Weather Forecasts, the ensemble shows sea surface temperatures rising up to 6.8 degrees F (3.8 degrees C) above average by December. That’s well into “super” El Niño territory.
In many parts of the world, the intensity of this event will likely exacerbate extreme weather events that are already growing more frequent and severe due to human-caused climate change. At the same time, all the extra heat the Pacific will pump into the atmosphere will amplify global warming, boosting Earth’s average temperature to new heights.
Now that NOAA has declared El Niño officially underway, federal forecasters will be watching closely for its impacts. While the true severity of this event remains to be seen, experts are urging decision makers and the public to be prepared for the worst-case scenario.
