NOAA raises probability of historic-strength El Niño to 75% for 2026–27 Northern Hemisphere winter
NOAA now puts the odds of a very strong El Niño during the Northern Hemisphere fall and winter of 2026–27 at greater than 90% — and the chances of a historic-strength event at 75%. The agency’s September 10 ENSO Diagnostic Discussion confirmed that El Niño conditions kept strengthening through early September, with more intensification expected through year’s end.
A historic-strength designation, by NOAA’s definition, would mean an event potentially exceeding any El Niño on record since 1950.
NOAA issues updated El Niño probability assessment
NOAA’s September 10 ENSO Diagnostic Discussion marks a real shift in how forecasters are framing the coming winter. El Niño conditions didn’t just hold through early September — they got stronger. NOAA expects that trend to continue through the end of the year.
NOAA points to a combination of ocean and atmospheric indicators that are, in the agency’s own words, consistent with a strengthening El Niño pattern.
The numbers are hard to ignore. A greater than 90% probability for a very strong El Niño during Northern Hemisphere fall and winter 2026–27 is already notable, but the 75% likelihood attached to a historic-strength event pushes this forecast into genuinely rare territory.
NOAA’s “historic-strength” label carries a specific meaning: the event would need to surpass every El Niño recorded since 1950. That’s more than seven decades of climate data. Clearing that bar would make 2026–27 unlike anything in the modern observational record.
Ocean and atmospheric indicators driving the assessment
The elevated probabilities aren’t based on a single signal. NOAA points to a combination of ocean and atmospheric indicators that are, in the agency’s own words, consistent with a strengthening El Niño pattern.
The most visible driver is sea surface temperatures in the Pacific — described by NOAA as exceptionally warm, the kind of warmth that typically underpins strong El Niño development. Surface temperature anomalies in the central and eastern tropical Pacific are a primary metric forecasters watch, and right now those readings are pointing firmly in one direction.
Alongside that ocean signal, continued ocean-atmosphere coupling is reinforcing the pattern. When the ocean and atmosphere interact in ways that amplify rather than dampen the warming signal, El Niño tends to intensify. NOAA’s assessment is that both components remain aligned through year-end.
Warm surface temperatures combined with a coupled atmosphere are what drive the agency’s confidence in further intensification. Neither factor alone would justify a 75% historic-strength probability. Together, they do.
Potential regional weather impacts across North America
Strong El Niño events have a track record of reshaping winter weather patterns across North America — wetter and cooler conditions for parts of the southern United States, warmer and drier winters for the northern tier. But “tends to” carries a lot of weight in seasonal forecasting.
NOAA is careful to note that regional impacts aren’t guaranteed. Even during historically strong El Niño events, local outcomes can diverge significantly from the broad pattern. A region that typically sees wetter winters during El Niño years might not experience that in any given event.
Seasonal outlooks are framed as probabilities for exactly this reason. NOAA can say certain outcomes become more or less likely — not that they will or won’t happen. That distinction matters if you’re trying to plan around winter conditions.
Temperature shifts, changes in precipitation, and storm track variations are all possibilities for the 2026–27 winter. How much any specific region actually feels those effects will depend on factors that seasonal models can’t fully resolve months in advance.
Context: What a historic-strength El Niño would mean
To put the 75% historic-strength figure in perspective, it helps to look at what previous major El Niño events actually produced. The 1997–98 event is often cited as the benchmark — it drove flooding across California, drought across parts of Asia and Australia, and disrupted weather patterns on multiple continents. The 2015–16 event rivaled it on some ocean temperature metrics and generated its own round of global climate disruptions.
A 2026–27 event that exceeds both would be, by definition, without modern precedent. That’s what NOAA’s historic-strength threshold actually means — not just a strong El Niño, but one that rewrites the record going back to 1950.
Energy market participants pay close attention to seasonal climate outlooks for exactly this reason. Winter demand for heating, electricity generation, and related commodities can shift meaningfully depending on whether temperatures run above or below normal across key population centers. A historic El Niño would carry real implications for those patterns, though the regional specifics remain uncertain.
NOAA’s ENSO Diagnostic Discussions are published regularly by the Climate Prediction Center, designed to update probabilities as new data arrives. The current figures will keep getting refined as the season approaches.
Further intensification expected through year-end
The core facts are straightforward. NOAA has assigned a greater than 90% probability to a very strong El Niño for Northern Hemisphere fall and winter 2026–27. The likelihood of a historic-strength event — one that would exceed any El Niño since 1950 — stands at 75%. Ocean surface temperatures and ocean-atmosphere coupling are both driving the assessment, with further intensification expected through year-end.
Regional weather impacts across North America remain probabilistic, not certain. Seasonal outlooks shift the odds; they don’t determine local outcomes. As conditions evolve, NOAA’s Climate Prediction Center will continue issuing updated assessments.
Kelly is an experienced writer with 15 years of experience exploring the big stories that shape our world, from tech breakthroughs and space exploration to climate, energy, and the fascinating quirks of science. She has a talent for turning complex ideas into sharp, memorable insights that stay with readers long after they’ve finished reading.
