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 teenager has been struck by lightning during dangerous thunderstorms in Queensland's south-east that caused structural damage and left thousands without power.
Following a run of cooler than average temperatures during the first half of next week, southwestern parts of Western Australia will see a return of hot conditions.
A burst of hazy heat enveloped Sydney on Friday, with temperatures just not letting up well into the evening.