Every El Niño and La Niña event since 1950, classified by peak strength — based on NOAA CPC's ONI methodology, with RONI-era notes where the classification differs.
This table tracks every El Niño and La Niña event in the NOAA instrumental record back to 1950, classified by peak strength using the Oceanic Niño Index (ONI) — three-month-average Niño 3.4 sea surface temperature anomalies versus the 1991–2020 base period. Where the newer Relative Oceanic Niño Index (RONI, NOAA's standard since February 2026) shifts a classification, that's noted separately. This page is updated as each new season's data is finalized by CPC.
El Niño: Weak 0.5–0.9°C · Moderate 1.0–1.4°C · Strong 1.5–1.9°C · Very Strong ≥2.0°C
La Niña: Weak −0.5 to −0.9°C · Moderate −1.0 to −1.4°C · Strong ≤ −1.5°C
| Event | Peak Season | Type | Strength | Notes |
|---|---|---|---|---|
| 1957-58 | NDJ | El Niño | Moderate | — |
| 1965-66 | NDJ | El Niño | Moderate | — |
| 1972-73 | NDJ | El Niño | Very Strong | First "Super El Niño" of the satellite-adjacent era |
| 1973-74 to 1975-76 | — | La Niña | Strong (multi-year) | — |
| 1982-83 | NDJ | El Niño | Very Strong | Caught forecasters off guard; reshaped ENSO monitoring |
| 1988-89 | NDJ | La Niña | Strong | — |
| 1991-92 | NDJ | El Niño | Moderate | — |
| 1997-98 | NDJ | El Niño | Very Strong | Peak ~+2.3°C; benchmark event, see our refresher |
| 1998-99 to 2000-01 | — | La Niña | Strong (multi-year) | — |
| 2007-08 | NDJ | La Niña | Strong | — |
| 2009-10 | NDJ | El Niño | Moderate | — |
| 2010-11 | NDJ | La Niña | Strong | — |
| 2015-16 | NDJ | El Niño | Very Strong | Peak ~+2.6°C; strongest on record per ONI, see our comparison |
| 2017-18 to 2022-23 | — | La Niña | Strong (near-continuous, "triple-dip") | RONI reclassifies this stretch as one continuous event |
| 2023-24 | NDJ | El Niño | Strong | One of the five strongest El Niños on record |
| 2024-25 | — | La Niña | Weak | Brief, weak event |
| 2025-26 | — | Neutral / Weak La Niña | Weak / Neutral | RONI read this stretch as definitive weak La Niña where ONI read neutral |
| 2026-27 | NDJ (forecast) | El Niño | Developing — Very Strong Likely | Advisory issued June 11, 2026; 60–63% NOAA probability of "very strong." See our live tracking coverage |
This table covers major/notable events and is not an exhaustive season-by-season listing of every weak/borderline fluctuation since 1950. For the complete official record, see NOAA CPC's ONI and RONI data files directly.
ONI (Oceanic Niño Index) is the raw three-month-average sea surface temperature anomaly in the Niño 3.4 region. RONI (Relative Oceanic Niño Index) subtracts the tropical-mean SST anomaly first, which accounts for long-term ocean warming and became NOAA's official standard in February 2026. Read our full RONI vs ONI explainer.
NOAA classifies El Niño strength by peak seasonal anomaly: weak (0.5 to 0.9°C), moderate (1.0 to 1.4°C), strong (1.5 to 1.9°C), and very strong (2.0°C or higher), measured as a three-month running average in the Niño 3.4 region.
The 2015-16 El Niño is generally considered the strongest in the NOAA instrumental record since 1950, narrowly surpassing 1997-98 — though the exact ranking can shift slightly depending on whether ONI or RONI methodology is applied.
For live, current-season tracking, see the RONI panel and SST spaghetti chart on our dashboard.