The NINO3.4 index is one of several El Niņo/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 Niņo 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 Niņo or La Niņa event is identified if the 5-month running-average of the NINO3.4 index exceeds +0.4°C for El Niņo or -0.4°C for La Niņa for at least 6 consecutive months.
Thousands of north Queenslanders are being evacuated as Cyclone Debbie bears down on the coast, bringing winds of up to 300 kilometres per hour and possibly a four-metre storm surge.
Evacuations have been ordered in coastal towns and communities in the Whitsundays and Burdekin regions in north Queensland as Tropical Cyclone Debbie bears down, with authorities warning of damaging tidal surges.
Tropical Cyclone Debbie continues to strengthen over the Coral Sea as Queensland residents prepare for destructive weather in the days ahead.