10 Highest Peaks in Completed El Niño Warm Episodes, 1950–2025 (ONI v6)

The largest completed warm-episode peak in NOAA’s ERSSTv6 ONI table is +2.6°C in the 2014–2016 threshold run, ahead of +2.4°C in 1997–1998 and +2.1°C in 1982–1983. The comparison uses observed historical values through 2025; the ongoing 2026 episode is excluded because its final peak is not yet known.

Method: read all 1950–2025 seasons in order, identify consecutive runs with ONI at or above +0.5°C lasting at least five overlapping three-month seasons, then take the maximum published value within each run. Rank the completed runs and retain all ties at tenth place. Labels show the first and last NOAA year labels in the threshold run; 2014–2016 is therefore broader than the familiar 2015–2016 event label.

ONI is a sea-surface-temperature anomaly in the Niño 3.4 region, not a global temperature anomaly, rainfall forecast or measure of damage. NOAA now uses the Relative Oceanic Niño Index (RONI) for official ENSO monitoring and prediction; ONI remains available for historical analysis. Do not directly mix this v6 series with older v5 values or seasonal model forecasts.

Sources checked October 26, 2026. Equal values represent ties; display order does not break a tie.