The NINO3.4 index is one of several El Niño/Southern Oscillation (ENSO) indicators based on sea surface temperatures.
NINO3.4 is the average sea surface temperature anomaly in the region bounded by 5°N to 5°S, from 170°W to 120°W. This region has large variability on El Niño time scales, and is close to the region where changes in local sea-surface temperature are important for shifting the large region of rainfall typically located in the far western Pacific.
An El Niño or La Niña event is identified if the 5-month running-average of the NINO3.4 index exceeds +0.4°C for El Niño or -0.4°C for La Niña for at least 6 consecutive months.
Blustery winds and thunderstorms are lashing Victoria today as a cold front sweeps across the state.
As Tropical Cyclone Debbie strengthens off the coast near Townsville in north Queensland, residents are being warned to prepare for the worst storm to hit the state since Cyclone Yasi in 2011.
Thousands of north Queenslanders are being evacuated as Cyclone Debbie bears down on the coast, bringing winds of up to 240 kilometres per hour and possibly a four-metre storm surge.