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.
Australia's energy operator has found power plant failures contributed to the unprecedented pressure on the New South Wales electricity grid during this month's heatwave.
Flying fox rescuers in Sydney are experiencing "the worst season ever" as a record number of bats get caught and injured in nets used to protect backyard fruit trees.
With a few days to go until the official end to the summer season, it looks like parts of New South Wales could still see the odd drop of rain.