These bone-chillingly cold mornings look set to continue until the weekend, with temperatures expected to stay below zero.
Weatherwatch.co.nz's Philip Duncan says the country was sitting under a large system of high pressure coming over from the west.
While it will linger for a few days, a "sharp" cold snap will bring rougher weather and sub-zero temperatures in a wider portion over the inner portion of the North Island, bringing more frosts.
Kiwis woke up to a thick frost both underfoot and coated over their vehicles, with some even struggling to open their doors.
St Arnaud in Nelson Lakes was -6C this morning and Waiouru was the coldest place in the North Island with -4.5C. Mt Cook village only got to -5.3C.
Auckland had its coldest morning in three years, getting down to -2.4C, while Hamilton was -3C.
Duncan says low overnight temperatures will remain the norm over the next days due to recent cold southerlies.
"Sub-zero minimum temperatures are possible in wide areas over interior North Island, rising the risk of frost. Coastal areas have more of a breeze and clouds which may keep temperatures above zero for the most part."
Dry weather will hang around for a few days before the front lands on Saturday.
"For Wednesday, the exception for sunny weather is mostly Southland, where persistent southwesterly winds bring low clouds and maybe light showers.
"Clouds with southwesterly winds may also spread over coastal areas in Wellington and Gisborne."
MetService meteorologist Tui McInnes said the weather will slightly ease over the course of today and tomorrow, before it starts to plummet again on Friday.
"With this high sitting over us, we are going to see some temperatures drop even further. We might find that is a particularly chilly start to the weekend," he said.