The short version
As of September 10, 2026, NOAA CPC says El Niño is strengthening with a greater than 90% chance of becoming very strong during Northern Hemisphere fall and winter 2026–27. CPC also gives a 75% chance that the October–December 2026 RONI exceeds +2.5°C, a threshold that would surpass previous events in the historical record back to 1950.
What the current U.S. outlook favors
NOAA's long-lead outlook increasingly leans on El Niño as winter approaches. Broadly, warmth is favored across the northern tier, while a wetter southern storm track becomes more prominent through winter. California and the Southeast receive some of the stronger winter precipitation signals. Parts of the inland Northern Rockies, Northern High Plains and Great Lakes retain a drier tilt.
Why this event is especially interesting
The tropical Pacific is not merely crossing the El Niño threshold. NOAA reports August Niño-3.4 at +1.8°C, Niño-3 at +2.5°C and Niño-1+2 at +3.4°C, with very warm subsurface anomalies as well. Stronger events tend to produce a clearer atmospheric response, although the exact U.S. winter still depends on other patterns.
When the signal should matter most
El Niño influence on U.S. climate is usually strongest in winter. CPC’s current discussion says impacts should ramp up from late fall into core winter, with some precipitation signals strengthening further into late winter.
What to watch next
- September 17, 2026: the next set of official CPC long-lead seasonal outlooks.
- October 8, 2026: next ENSO Diagnostic Discussion.
- Whether the very strong/historic-strength probabilities remain elevated.
- Whether regional precipitation maps sharpen or shift as winter gets closer.