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 tropical low brewing 600 kilometres north-east of the Queensland coast could make landfall somewhere between Cairns and Townsville early next week as a category four cyclone or higher, the Bureau of Meteorology (BOM) says.
Cyclone preparation comes second nature to many north Queenslanders.
Sydney is having its wettest March in 33 years after yet another showery night.