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.
Weather forecasters are predicting snow across Tasmania over the weekend and possible snow in Hobart for the first time since 1986.
Strengthening El Nino to reduce rainfall in northern and south-east Australia but wetter conditions for Western Australia
The Bureau of Meteorology has confirmed the El Nino pattern is strengthening in the Pacific and is likely to persist into next year.
An unusual weather pattern is bringing storms to parts of southern Western Australia, with residents in the Central West, Lower West, Great Southern and Central Wheatbelt districts told to brace for damaging winds and possible flash flooding.