The 2026 Timeline
The defining feature of the 2026 event is how fast it flipped. The Oceanic Niño Index went from −0.21°C in January-March to +1.39°C in May-July — one of the sharpest La Niña-to-El Niño turns on record, and the shortest gap between a La Niña and an El Niño since 1963.
What Happened When
| Date | Milestone | ONI / Detail |
|---|---|---|
| Jan–Mar 2026 | La Niña tail end | ONI −0.21°C (JFM) |
| Feb–Apr 2026 | Rapid warming begins | ONI +0.11°C (FMA) |
| Mar–May 2026 | Crosses toward neutral | ONI +0.46°C (MAM) |
| Apr–Jun 2026 | Approaches El Niño threshold | ONI +0.95°C (AMJ) |
| June 11, 2026 | NOAA declares El Niño conditions | Threshold +0.5°C crossed |
| May–Jul 2026 | Event strengthens | ONI +1.39°C (MJJ) |
| Aug–Sep 2026 | Super El Niño watch | CPC 63% chance of Super strength |
| Nov–Jan 2026-27 | Projected peak | Most likely NDJ window |
What Comes Next
The Climate Prediction Center gives a 63% probability this event reaches Super El Niño strength (ONI of +2.0°C or higher) by the 2026-27 winter, with the peak most likely in the November-December-January window. If that happens, 2027 could become the hottest year ever recorded, eclipsing 2023-24 and 2015-16.
For region-by-region impacts as the event unfolds, see the global impacts guide and the seasonal forecast breakdown. The live numbers update on the El Niño Tracker each month as NOAA publishes new ONI data.