Nino 4

Indices

Nino 4 sits near the date line, on the edge of the warm pool. Its temperature changes less than the eastern boxes.

In September 2026 the CPC reported Nino 4 at only +0.1 °C: the 2026 event is concentrated in the east.

Sources

• NCAR Climate Data Guide -- Nino SST indices
• NOAA CPC -- ENSO Diagnostic Discussion (monthly)

Related

• The Nino regions (1+2, 3, 3.4, 4)
• Nino 3.4
• Western Pacific warm pool

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)