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 wet winter is set to give way to a sneezy spring in south-eastern Australia, with this hayfever season predicted to be the worst in years.
Residents of Alice Springs have woken to thick fog blanketing the streets and cloaking the East MacDonnell Ranges.
An impending rain event scheduled for the opening days of spring continues the pattern of wet weather which has gripped eastern Australia during winter.