Parts of the lower South Island are sweltering with temperatures hitting the high 20s.
Photo: RNZ / Tracy Neal
Invercargill, Balclutha and Ashburton were 29 degrees today with other eastern areas in the mid to high 20s.
MetService meteorologist Rob Kerr said a warm north-west flow was behind the hot weather, which should continue into tomorrow.
"Across the South Island tomorrow we could see even warmer temperatures, we are looking at the possibility of 30 degrees for the likes of Christchurch and Blenheim, and mid to high 20s for the eastern South Island, from Gore all the way up to ... Nelson," he said.
It will be a bit windy through the lower North Island, so the temperatures won't be quite as high as those in parts of the South Island.
But eastern areas, like Napier and Gisborne, could hit 28 or 29, Mr Kerr said.
The weather should be fine and settled over the upper North Island, with highs in the mid-20s.
Mr Kerr said it was looking good across much of the country heading into New Year's Eve celebrations.
Meanwhile, a severe weather watch is in place for heavy rain in Fiordland and southern Westland.