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.
Parts of the New South Wales coast are in for their biggest downpours since last winter, bringing a much needed drink to gardens and parks but also causing some flooding.
After a respite from intense summer heat over the last couple of weeks, Adelaide is set to sizzle once again.
If you wanted to stay a bit warmer today, a dip in the ocean is probably your best bet, despite the rain.