ENSO (El Niño–Southern Oscillation)
Classification and Intensity Thresholds
El Niño events are classified by intensity based on sea-surface temperature anomalies in the Niño 3.4 monitoring region (5°N–5°S, 120°W–170°W) averaged over overlapping three-month periods:
- Weak El Niño: SST anomaly of 0.5°C to 0.9°C above normal.
- Moderate El Niño: SST anomaly of 1.0°C to 1.4°C above normal.
- Strong El Niño: SST anomaly of 1.5°C to 1.9°C above normal.
- Very Strong / Super El Niño: SST anomaly ≥2.0°C above normal.
- The 1997-98 El Niño (peak anomaly ~2.8°C) and 2015-16 El Niño (peak ~2.3°C) are the two strongest events in the instrumental record.
- The 2023-24 El Niño was one of the five strongest on record and contributed significantly to 2024 being the warmest year globally.
- The current 2026 event, with WMO forecasting SST anomalies to exceed 2°C, would place it in the "very strong/super" category if sustained.
- An El Niño event is officially declared when the 5-month running mean of SST anomalies in the Niño 3.4 region exceeds +0.5°C for five consecutive overlapping seasons.
● Tracked since February 25, 2026 · last seen July 03, 2026 · updates as the daily brief publishes
03 Jul '26
WMO Warns of Strong El Niño Driving Extreme Weather Globally in 2026
Environment & Ecology
11 Jun '26
El Niño 2026: Global Extreme Weather Risks and Climate Amplification
Environment & Ecology
24 Apr '26
El Nino Likely to Return by Mid-2026: WMO Forecast and What It Means
Environment & Ecology
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