NIWA weather forecaster Chris Brandolino says there is now about a 95 percent chance that an intense El Nino weather pattern will persist into spring and summer.
El Nino is associated with a band of warm ocean water that develops in the central equatorial Pacific, and can bring drier conditions to the east coast of New Zealand and wetter conditions in the West.
Mr Brandolino said the ingredients were there for an intense El Nino, but that did not neccesarily translate to intense impacts for New Zealand.
"For New Zealand, it only accounts for about 25 percent of our temperature and precipitation variability. What does that mean? It's a climate driver," he said.
"It's an important piece of understanding what drives the climate - what's the steering wheel? However, there are other climate drivers that impact New Zealand weather and El Nino is just one of them. It's only about 25 percent.
"In some years, there have been huge impacts. 1997/98 - that was an intense El Nino. There were very dry conditions on the East side of the North and South Island so there can be some really negative outcomes with an intense El Nino."
He said that very dry weather throughout the winter in parts of Hawke's Bay and Canterbury could result in very difficult conditions in the coming months with the influence of El Nino.