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 gusty cold front has brought entirely new weather to New South Wales in the last day, and even some late snow! Many a New South Welshman experienced a sweaty night's sleep last night after a hot day.
Despite recent rainfall across parts of western Queensland, residents will gather in the north-west today to pray for drenching rain.
For the last four years Central Australia's Elkedra cattle station has received around half its average annual rainfall or only 150 millimetres each year.