Could 2026-2027 El Niño Rewrite the Record Books?

NOAA’s Latest El Niño Outlook

For my first Tom the Weather Wizard blog post, there could hardly be a bigger weather story: the strengthening El Niño in the tropical Pacific may challenge the modern record. According to NOAA’s August 24 ENSO briefing, there is at least a 90% chance of a very strong El Niño during the overlapping September–November through November–January seasons.

For October–December, NOAA gives a 69% chance that the Relative Oceanic Niño Index, or RONI, reaches +2.5°C or higher—a level that would exceed every event in its record dating to 1950. For the same November–January season, the probability of a very strong event rose from 25% in April to 63% in June and 90% in August.

This does not prove a record will be broken, and it does not establish the strongest El Niño in Earth’s entire history, but it shows how dramatically NOAA’s confidence in an extreme event has increased.

What is the ENSO Cycle?

El Niño, La Niña and ENSO-neutral are the three states of the El Niño–Southern Oscillation, a natural interaction between the tropical Pacific Ocean and the atmosphere. Under NOAA’s current RONI framework, El Niño is associated with relative warmth of at least +0.5°C in the Niño 3.4 region, accompanied by a consistent atmospheric response; La Niña is its cool counterpart at −0.5°C or lower, while neutral falls between those thresholds.

Neutral does not mean the weather everywhere will be “normal”—only that neither ENSO phase is dominating the tropical Pacific. ENSO also does not affect the United States more than every other part of the world; its changes in rainfall and atmospheric circulation can be enormously consequential across Australia, Indonesia, Africa and South America.

Its influence on the United States becomes especially recognizable during winter because tropical Pacific heating can generate large atmospheric waves that alter the powerful North Pacific jet stream and downstream weather patterns across North America.

A Typical El Niño Winter in the USA

The classic El Niño winter features a stronger, more extended subtropical jet and a more active southern storm track. That generally tilts the odds toward warmer conditions across the northern United States and wetter—and sometimes cooler—weather across portions of the southern tier. It does not automatically mean the entire South will be snowier, because additional precipitation only becomes snow when sufficient cold air is available.

NOAA’s current seasonal outlook discussion favors above-normal temperatures with probabilities exceeding 50% from the Pacific Northwest to the Northeast by December–February. Much of the Southeast is favored to finish closer to normal as El Niño’s historical cooling influence competes with recent warm temperature trends. During parts of late fall and winter, above-normal precipitation is favored across much of the southern tier, California and portions of the East Coast.

Stronger El Niño events often increase confidence in familiar impacts rather than causing those impacts to reverse, but this event’s exceptional projected magnitude and eastern-Pacific orientation could push it beyond the range of direct modern comparisons.

Other Meteorological Variables That Could Influence Winter 2026-2027

An energized subtropical jet can support moisture-rich storms from California across the southern states and, at times, along the East Coast. That creates opportunities for significant systems this winter, but a seasonal outlook cannot determine how many major storms will occur or whether they will produce rain, snow, ice or severe weather.

For Pennsylvania and the Mid-Atlantic, the crucial ingredient will be whether southern-stream energy can meet an available source of cold air. El Niño winters can reduce the frequency of Arctic outbreaks into the central United States because the polar jet often remains farther north, but a warmer seasonal average never eliminates short, intense cold waves.

The Arctic, North Atlantic and Eastern Pacific Oscillations, the Madden–Julian Oscillation and the behavior of the stratospheric polar vortex can still temporarily open the door to Arctic air. Other variables—including the event’s eastern-Pacific placement, the preceding La Niña winter, ocean temperatures outside the tropics, sea-ice extent, soil moisture and long-term climate trends—will also help determine how winter unfolds.

My Prediction: Why the 2026 El Niño May Surprise Us

My main takeaway is not that we already know winter 2026–27 will be historically warm, snowy or stormy. It is that El Niño has strengthened considerably, NOAA’s confidence in a very strong or potentially record-setting event has risen sharply, and the atmosphere may be entering territory with very few reliable modern analogs.

The broad starting point still favors northern warmth, a wetter southern tier and an energized southern storm track, but individual cold outbreaks could dramatically change the local winter-weather impacts when they overlap with that storminess. A season can average warmer than normal and still produce a memorable Arctic blast or major snowstorm.

This winter may reinforce several textbook El Niño signals, amplify them, shift their timing or surprise us regionally. The uncertainty is not a weakness in the forecast—it is the most important part of the story, and Tom the Weather Wizard will be following every update as this potentially historic event evolves.