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.
Snow is falling in Hobart's central business district and across the state, prompting the closure of many roads and schools.
Spring-like temperatures are bathing central and northern parts of New South Wales today, with some places experiencing record temperatures for this time of the year.
Areas of rain rolled across southern New South Wales yesterday and into early this morning, bringing some of the best August rainfall in several years for some places.