Much of the country had a frosty start on Tuesday with a second day of cold early morning temperatures.

MetService meteorologist Ashlee Parkes said some of the coldest temperatures in the North Island, seen around 5am Tuesday morning, included southern Waioru at -7.7C and the Desert Road at -6.8C.

The South Island didn't escape the cold either, with MetService recording -4.5C at Pukaki Airport and -3C in Alexandra.

"Most places are not as cold this morning [as] they were yesterday morning," Parkes said.

"The one exception to that that I could find was Hamilton Airport, which was -3.2C at 5am this morning and that is their coldest temperature measured this year."

She said a front approaching on Wednesday would see a slight warming of temperatures, especially for the South Island.

Tuesday's chill follows a cold and frosty morning around the country on Monday, with Taupō falling to -5.6°C and Christchurch reaching -4.7°C.

MetService said it expected the frosty mornings to continue through the first half of the week, especially across the North Island.

Meteorologist Devlin Lynden earlier said the cold start was being driven by clear skies and light winds.

"With calm, clear nights, heat escapes easily into the atmosphere, allowing temperatures to plummet before sunrise. Sheltered inland valleys become even frostier as cold air settles into low-lying areas."

While there was another cold start on Tuesday morning, overnight temperatures later in the week should be warmer as northerly winds develop.

The South Island has also seen frosty mornings, although increasing northerly winds have prevented temperatures from dropping too harshly.

Those winds should strengthen through Tuesday and Wednesday ahead of a front bringing a change in the weather toward the rest of the week.

Power demand surges

Transpower NZ said the cold weather this week was leading to record electricity demand, with Monday's peak demand of 7141 MW an all-time record.

Transpower - which is responsible for maintenance and transmission of the electric power grid - said it was working with the electricity sector to increase the amount of electricity that is available.

"We aren't anticipating any impact on power supply to homes or businesses."

Speaking to Morning Report, operations manager Chantelle Bramley said the response from power companies has been "excellent" with more generation being offered.

It wasn't common for Transpower to issue such notices, Bramley said, with the recent notices the first time this year. she said they had last issued such notices in October 2025.

As well as the record high on Monday morning, Bramley said demand was also high Monday evening and this morning, too.

Transpower would be continuing to monitor demand over the coming days but the transmission grid was "in good shape".