NINO.WEST (western Pacific warm pool)

Indices

JMA's NINO.WEST index is the monthly SST anomaly over Eq-15N, 130E-150E. The same collector also stores JMA's NINO.3 (5N-5S, 150W-90W), JMA's main El Nino index. Series nino_west_jma_anom, nino3_jma_anom (degC).

Limits. Monthly, preliminary for the latest month.

How to read it

During El Nino the warm pool usually cools relative to normal while NINO.3 warms. A cool warm pool means less rising air and fewer rain clouds near the Philippines and South-East Asia.

Why it matters for Koh Samui

Less convection over the western Pacific is one of the ways El Nino reduces rainfall over Thailand and shifts where typhoons form.

Sources

• ds.data.jma.go.jp
• ds.data.jma.go.jp

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)