El Nino Watch

ASEAN seasonal outlook (ASMC)

The regional climate centre's outlook for rain, temperature and haze in South-East Asia for the coming month and season.

Forecasts and bulletins

The ASEAN Specialised Meteorological Centre (a WMO Regional Climate Centre) publishes early each month a multi-model outlook for the ASEAN region, with the El Nino context and the smoke-haze risk. We keep the overview, the 'Mainland South-East Asia' paragraphs and the maps.

Limits. Regional, not specific to Samui; national services (TMD) have the final word. Updated once a month.

How to read it

Terms: below-normal / near-normal / above-normal = the lower, middle or upper third of past years. 'Model skill' says how much to trust the forecast for that area.

Why it matters for Koh Samui

The official regional view of what El Nino means for rain and haze in Thailand for the next 3 months. September 2026 issue: below-normal rainfall and above-normal temperature for most of the region.

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)