NIWA's predicting a warmer than average start to winter with only occasional frosts and cold spells.
Its climate outlook summary for May to June forecasts temperatures are "very unlikely" to be colder than average over the next three months as a whole.
"Above-average or near average temperatures are favoured for all regions except the east of the South Island, where above-average temperatures are most likely," it says.
"While frosts and cold spells will occur occasionally, they are generally expected to be brief."
On the rain front, NIWA says it's possible the long dry spells New Zealand's been experiencing continue over the next three months.
"Rainfall is about equally likely to be below normal or near-normal in all regions of Aotearoa New Zealand except the north of the North Island, where near-normal rainfall is most likely," it says in its release.
"While rainfall events will occur over the next three months, their frequency may be reduced compared to normal. Groundwater and dam level recharge and increases in river flow and soil moisture will likely be less pronounced than normal."
And with air pressure predicted to be higher than normal to the east of the country, New Zealand is expected to see more westerly and northeasterly quarter winds than normal.
