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.
South Australians are waking to assess the damage amid rising floodwaters, after two nights of severe weather that battered much of the state.
Winds sweeping South Australia have plunged thousands of residents into darkness again for another night only a day after the entire state suffered a blackout.
South Australia has been lashed with severe weather for the second night in a row, with strong winds battering much of the state.