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.
Storm-force winds forecast to hit South Australia this week will be the strongest the state has had in more than 50 years, the weather bureau has warned.
Heavy rains across New South Wales have farmers reassessing possible machinery purchases despite their still expressing interest in new equipment.
Australia's tropics are acting like it's already the wet season, even though September is technically the final month of the dry.