Temperatures dropped to below zero in much of the North Island overnight, and Invercargill was warmer than Auckland, as the wintry weather headed north.
Waiouru in the central North Island plummeted to a chilly -7°C degrees, Taupo went to -5°C, while Rotorua and Hamilton dipped to -3°C, and Whenuapai, in the Waitakere Ranges, was as low as -2°C.
Auckland motorists were faced with the unfamiliar sight of ice on car windscreens this morning as the temperature fell to an unusual 1°C.
That was lower still than Saturday night's 1.4°C - the city's coldest temperature in two years.
Whangarei managed a record of sorts with its 8th coldest morning since 1967, according to NIWA.
Cloudy weather in the south meant Dunedin was a balmy 6°C degrees and Invercargill and Queenstown were 5°C.
Many inland roads were covered in black ice, and police and transport authorities warned drivers to take extra care on the Napier-Taihape and Napier-Taupo roads and in the Coromandel area.
Temperatures were due to warm up tomorrow as cloud increased and rain came in from the west.
A soggy Wellington is in for more rain tomorrow, with MetService issuing a severe weather watch for Westland and the lower North Island.
"Given the sodden conditions, even lesser amounts such as 25 to 40mm falling in under 12 hours could cause further issues, such as surface flooding and slips."
Multiple slips in Wellington last week forced the evacuation of some houses and closed Ngaio Gorge.