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 category one cyclone has formed in the Gulf of Carpentaria but is due to weaken before heading towards the Northern Territory coast.
Shacks in the fishing village of King Ash Bay in the Northern Territory's Gulf of Carpentaria have been flooded by the McArthur River.
Early today, a tropical low that has been lingering over the Gulf of Carpentaria was upgraded to tropical cyclone.