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.
WA's Kimberley is in the midst of one of its biggest wet seasons on record, causing headaches for emergency services, remote communities and cattle stations cut off by flooding, but it has not been all bad news for the region.
Some homes in the community of Borroloola on the Gulf of Carpentaria have been evacuated with 74 residents sheltering elsewhere, as they wait for Cyclone Alfred to make landfall about sunrise on Tuesday.
Shacks in the fishing village of King Ash Bay in the Northern Territory's Gulf of Carpentaria have been flooded by the McArthur River.