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.
The Bureau of Meteorology says spring could be wetter than normal for much of western and central Australia.
Papua New Guinea's prime minister Peter O'Neill says he may review a recent ban on importing Australian fruit and vegetables into the country.
Warragamba Dam in Sydney has begun spilling following days of heavy downpours, as residents on the New South Wales south coast count the cost of flood damage.