The Pacific Ocean is set to enter into an extreme warm weather pattern over the next three months.
El Nino patterns, last seen in 2012, are usually characterised by reduced easterly trade winds and warmer sea surface temperatures around the datelines in the equatorial Pacific.
The imminent change has been monitored by buoy and satellite measurements which show the ocean is warmer than usual, but the easterly trade winds in the central Pacific are still blowing at their usual strength for the time of year.
The signal of an El Nino pattern has not yet been seen in atmospheric circulation.
In El Nino years, New Zealand usually experiences stronger or more frequent winds, which bring moist, rainy conditions to the northeast parts of the North Island, according to the National Institute of Water and Atmospheric Research.