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.
Tropical Cyclone Debbie is just hours from reaching the north Queensland coast.
Torrential rain is falling in Mackay and local authorities have issued a storm surge warning as Tropical Cyclone Debbie makes its presence felt in the north Queensland city.
As north Queensland prepares for Cyclone Debbie and wind gusts of up to 240 kilometres an hour, there's one surprising factor that could affect how seriously locals are taking the storm.