NOAA Raises Odds of Historic-Strength El Niño to 75% for Oct-Dec 2026

NOAA's Climate Prediction Center, in its Sept. 10 ENSO Diagnostic Discussion, raised the probability of a historic-strength El Niño during October-December 2026 to 75%, up from 69% in its mid-August assessment, after the coupled ocean-atmosphere event strengthened further across the tropical Pacific. CPC also raised the probability of a very strong event during the same window from 95% to 98%. CPC defines a historic event as an October-December three-month RONI reading of +2.5°C or higher, which would exceed the strength of every El Niño in its record dating to 1950. NOAA noted that with an event of this magnitude, 'the chances of experiencing impacts consistent with El Niño are larger, though not guaranteed.'