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.
More than a dozen homes have lost their roofs and close to 19,000 properties were left without power after very dangerous thunderstorms tore across south-east Queensland on Sunday afternoon.
Several people including babies have been rescued from Lismore Base Hospital in northern New South Wales after the roof of the maternity ward collapsed.
Severe thunderstorms caused damage in northeastern New South Wales and southeast Queensland on Sunday and should do so again during the next few days.