El Nino Watch

ECMWF Nino 3.4 forecast plume

The European centre's monthly seasonal forecast of the Nino 3.4 temperature anomaly for the next 6 months, as a chart.

Forecasts and bulletins

Each month ECMWF runs its SEAS5 seasonal model 51 times with slightly different starting states. The plume chart shows every run's Nino 3.4 anomaly: thin red lines are the forecasts, the dashed line the observations. Two versions are kept: absolute and relative (RONI-like) index.

Limits. A picture, not numbers: we store the chart link only. Model forecasts made in spring are less reliable (spring barrier). Chart (c) ECMWF, CC-BY-4.0.

How to read it

If most lines stay above +2 C, a very strong El Nino is forecast to continue; the spread of the lines is the uncertainty. Status key ecmwf_nino_plume {issued, label, images}.

Why it matters for Koh Samui

A second opinion next to NOAA's and IRI's outlooks: when independent centres agree, confidence is higher about how long El Nino-type conditions will last over Samui.

Sources

ENSO status now

ONI (NOAA CPC)
+1.80 °C, JJA 2026 (previous +1.39 °C)
RONI (NOAA CPC)
+1.36 °C, JJA 2026
Nino 3.4 weekly (NOAA CPC / OISST)
+3.0 °C anomaly, week of 16 Sep 2026 (SST 29.6 °C)