Relative Oceanic Niño Index (RONI, °C), three-month averages, from the start of each event's onset year. The shaded band is NOAA's September forecast for 2026.
| Season | 1972-73 | 1982-83 | 1997-98 | 2015-16 | 2023-24 | 2026-27 | 2026 CPC forecast median (5–95%) |
|---|---|---|---|---|---|---|---|
| DJF (onset yr) | -0.21 | 0.11 | -0.21 | 0.54 | -0.86 | -0.91 | |
| JFM (onset yr) | 0.03 | 0.22 | -0.03 | 0.47 | -0.68 | -0.76 | |
| FMA (onset yr) | 0.32 | 0.23 | 0.17 | 0.59 | -0.55 | -0.44 | |
| MAM (onset yr) | 0.51 | 0.46 | 0.47 | 0.72 | -0.31 | -0.04 | |
| AMJ (onset yr) | 0.66 | 0.74 | 0.83 | 0.89 | -0.04 | 0.49 | |
| MJJ (onset yr) | 0.87 | 0.84 | 1.2 | 1.02 | 0.28 | 0.97 | |
| JJA (onset yr) | 1.14 | 0.89 | 1.5 | 1.27 | 0.54 | 1.36 | |
| JAS (onset yr) | 1.4 | 1.14 | 1.84 | 1.54 | 0.79 | ||
| ASO (onset yr) | 1.64 | 1.64 | 2.07 | 1.8 | 1.04 | 2.07 (1.80–2.34) | |
| SON (onset yr) | 1.82 | 2.03 | 2.22 | 2.03 | 1.3 | 2.43 (2.01–2.85) | |
| OND (onset yr) | 1.97 | 2.24 | 2.25 | 2.18 | 1.42 | 2.67 (2.12–3.23) | |
| NDJ (onset yr) | 1.88 | 2.36 | 2.28 | 2.25 | 1.4 | 2.57 (1.87–3.26) | |
| DJF (next yr) | 1.69 | 2.4 | 2.13 | 2.14 | 1.13 | 2.27 (1.48–3.06) | |
| JFM (next yr) | 1.25 | 2.15 | 1.82 | 1.81 | 0.78 | 1.82 (1.04–2.59) | |
| FMA (next yr) | 0.58 | 1.67 | 1.22 | 1.3 | 0.42 | 1.26 (0.56–1.95) | |
| MAM (next yr) | -0.17 | 1.3 | 0.81 | 0.65 | 0.04 | 0.79 (0.17–1.42) | |
| AMJ (next yr) | -0.73 | 0.87 | 0.07 | 0.08 | -0.28 | 0.38 (-0.27–1.04) | |
| MJJ (next yr) | -0.98 | 0.47 | -0.46 | -0.43 | -0.45 |