ENSO Diagnostic Discussion: El Niño Advisory issued 10 September 2026

The NOAA Climate Prediction Center diagnostic discussion reports that El Niño continues to strengthen and has a greater than 90 percent chance of becoming a very strong event during the Northern Hemisphere fall and winter of 2026-27. During August, sea surface temperature anomalies increased across the central and eastern equatorial Pacific: the Niño-3.4, Niño-3, and Niño-1+2 indices reached +1.8°C, +2.5°C, and +3.4°C, respectively. The official outlook also indicates a 75 percent chance of a historic event during October-December 2026, defined by a three-month RONI value of +2.5°C or higher. NOAA notes that an event of this magnitude increases the likelihood of impacts consistent with El Niño, although those impacts are not guaranteed.