ENSO insight
A very strong El Niño is forecast.
Monthly rONI reached +2.08 in September 2026. The multi-model median peaks at +3.34 in December 2026; CPC's expected value for NDJ is +2.23 on a 3-month mean.
Observed, Sep 2026
+2.08
Monthly rONI.
Multi-model median peak
+3.34
December 2026. Interquartile range +3.01 to +3.57.
CPC expected value, NDJ
+2.23
3-month mean, ±1σ +2.13 to +2.33. A forecaster consensus, not a model run.
Very strong, CPC
96%
Probability of rONI at 2.0 or more in NDJ.
Where the event is heading
Monthly rONI, observed and forecast
Hover to read each month. Observed and model values are monthly; the CPC diamonds are 3-month means placed at the centre month, so they are not directly comparable. Data: enso_plume_2026-10.csv, cpc_strengths_2026-10.csv; paths and links are under Sources.
CPC strength probabilities, NDJ
Probability of each El Niño strength class