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.
Temperatures will cool down for much of the week for South Australia, Victoria and New South Wales.
The monsoon trough has made a glancing blow of Queensland's Cape York Peninsula and the Top End.
Rain in parts of western Queensland in the past week has raised hope that the drought may finally be over, but the long, dry years have already devastated pastures and wiped out incomes for many farming families.