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.
Damaging winds are forecast to affect Victoria for the second time in two days as a cold front moves into the Bight.
For many Tasmanians it will be no surprise the heavy rains since the beginning of May have set a new three-month record, before the end of the period.
A flood watch is current in the Mount Lofty Ranges near Adelaide as another cold front approaches the region.