The hot weather is set to peak over the weekend, with MetService forecasting temperatures in the mid-thirties for towns on both Islands on Sunday and Monday.
In fact, the weather forecaster says heatwave conditions are likely for several locations.
MetService says it's being driven by a slab of humid air sliding towards New Zealand from the tropics this weekend in a northwesterly windflow.
But it'll also be windy - the northwesterlies will bring gales to the mountains and exposed areas near the coast.
MetService has several strong wind warnings in place, and although the wind will ease on Friday, it will be coming back with a vengeance on Saturday.
️Heat and humidity from the tropics for the weekend. Loop shows a tongue of hot, humid air sweeping over NZ this weekend, with expected max temps of 35C for several spots— MetService (@MetService) January 29, 2020
https://t.co/Yjbq0jxdqz ^TA pic.twitter.com/lCXsNVg7f1
Rain is also in the mix.
MetService said the humid air will bring persistent heavy rain to the southern West Coast and Fiordland between Sunday and Tuesday, with slips and surface flooding possible.
Meteorologist Tom Adams said the combination of warm, humid air with strong northwesterly winds leads to a marked heating effect in eastern areas.
"This will add several extra degrees to the already high air temperatures. Unfortunately, these warm temperatures will stick around at night too, meaning uncomfortably muggy conditions to sleep in."
It would be Tuesday at least before a cold front swept away the muggy air from the South Island before then weakening over the North Island.
Warm temperatures are likely to continue there well into next week.
That means that several locations were likely to meet heatwave conditions, where daily maximum temperatures exceed monthly averages by five degrees for five or more days in a row, MetService said.
Why so warm?— MetService (@MetService) January 29, 2020
This weekend and early next week are set to be unusually warm, with many areas showing heatwave potential. Warm, moist tropical air and a northwest wind are the cause, combining to cause the Foehn effect https://t.co/48UbWuP6lW ^TA pic.twitter.com/yq3fpbTQqd
Meanwhile, the National Institute of Water and Atmospheric Research (NIWA), has released its climate outlook for February to April.
For that period, temperatures are about equally likely to be near average or above average in all regions of New Zealand except the north of the North Island where above average temperatures are most likely.
Rainfall is most likely to be near normal in all regions of New Zealand except for the east of the South Island where normal or below normal rainfall is about equally likely.
Soil moisture levels and river flows are most likely to be below normal in the north of the North Island and west and east of the South Island, about equally likely to be near normal or below normal in the west and east of the North Island.