Data source: NOAA Climate Prediction Center. ONI values use 1991–2020 base period. Last updated: May 2026.
Oceanic Niño Index (ONI) — 1950 to Present
The ONI is NOAA's standard for classifying El Niño and La Niña events. El Niño = ONI ≥ +0.5°C for 5 consecutive overlapping seasons. La Niña = ONI ≤ -0.5°C for 5 consecutive overlapping seasons.
El Niño (≥ +0.5)
La Niña (≤ -0.5)
Neutral
Recent ONI Values
| Season | Year | ONI (°C) | Status |
|---|
ENSO Forecast Plume
The IRI/CPC ENSO forecast plume shows model predictions for Niño 3.4 SST anomalies over the next 9 months. Each line represents a different dynamical or statistical model.
IRI/CPC ENSO Forecast Plume — updated monthly. View full report
What is the Oceanic Niño Index?
The ONI is the de facto standard for measuring ENSO. It is the 3-month running mean of SST anomalies in the Niño 3.4 region (5°N–5°S, 120°W–170°W), relative to the 1991–2020 base period.
| ONI Range | ENSO State | Intensity |
|---|---|---|
| ≥ +2.0°C | El Niño | Very Strong |
| +1.5 ~ +1.9°C | El Niño | Strong |
| +1.0 ~ +1.4°C | El Niño | Moderate |
| +0.5 ~ +0.9°C | El Niño | Weak |
| -0.4 ~ +0.4°C | Neutral | — |
| -0.9 ~ -0.5°C | La Niña | Weak |
| -1.4 ~ -1.0°C | La Niña | Moderate |
| -1.9 ~ -1.5°C | La Niña | Strong |
| ≤ -2.0°C | La Niña | Very Strong |