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.
A dangerous trough and cold front is approaching south-west Western Australia, the Bureau of Meteorology (BoM) has warned.
Most of Hobart's Myer store could be open within days but it faces "devastating" stock losses and damage, manager Peter Monachetti says.
While much of Australia's mainland sits under a high pressure system, it's a different story for Tasmania.