Much of the country is shivering in sub-zero temperatures with Omarama and Middlemarch the coldest.

MetService said Middlemarch, in Otago, was the coldest in the country at -10.6C shortly and temperatures were close to -10C in the Canterbury town of Omarama.

Most of the South Island was at below zero temperatures, with Queenstown and Ashburton on -4C, Timaru -3C and Christchurch -2C at 6am.

Some flights at Dunedin Airport were cancelled due to the weather, and there were reduced bus services in the city because of road conditions.

Thursday is the coldest recorded day by MetService so far in 2022.

But Stewart Island was recording a relatively balmy 8C at 6am - the same as Napier and two degrees warmer than Auckland at 6C.

In the North Island, ten places were below zero degrees, with Raetihi in the central North Island the coldest at -4.4C.

The week has been dominated by high pressure, clear skies, and cold temperatures but MetService is forecasting a change in weather patterns for the weekend.

"There will be some slightly milder temperatures for the weekend," meteorologist Angus Hines said.

Cloudier skies and wetter weather return from the west later Friday and swing across the country during Saturday.

Matariki stargazing

Friday is likely to be the best chance over the long weekend for stargazers to see Matariki and Puanga in the early morning sky.

"Central and eastern parts of both islands ought to get a fairly clear view of the stars before sunrise," Hines said.

But along the West Coast, and for the upper North Island, cloud cover may spoil the view."

Cloud is expected to extend over many other regions during Friday, making the early hours likely to be the best viewing.

Sunday sees the return of some drier and brighter weather for most of Aotearoa New Zealand but still with some showers remaining for the west of the North Island, MetService says.