Parts of the country are in for another scorcher, with a heat alert for Auckland and Te Kuiti expected to hit 30C.

MetService has a heat alert in place for Auckland, with high sustained temperatures predicted.

Meteorologist Ngaire Wotherspoon says most of the upper North Island, including Whitianga, Tauranga, and Whakatāne, will see warm temperatures.

For locations under a heat alert, MetService says it advised to keep hydrated, seek shade, check in with vulnerable people and look after pets and livestock.

A cold change was expected on Friday and Saturday, Wotherspoon says, with a cold front moving up the country.

It will see temperatures drop in the South Island before picking up again early next week.

MetService says Alexandra and Taumarunui are forecasted to go from highs of 29C on Wednesday to just 18C and 19C respectively on Saturday.

"For those planning an extended weekend ahead of Waitangi Day, early indications suggest that, aside from the occasional shower in Fiordland, a ridge of high pressure is poised to bring settled weather on Monday and Tuesday for the rest of Aotearoa New Zealand."

On Tuesday, Tauranga Airport was the hottest location, recording a maximum temperature of 30.4C.

Twizel hit 30.1C.

Springs Junction has the coldest minimum temperature, at 5.7C.

-RNZ.