With temperatures dropping below zero during this morning's big chill, Kiwis are being urged to take extra care behind the wheel now winter has arrived.
Pukaki Airport - near Twizel in the South Island's Mackenzie District - was among the country's coldest spots overnight, dropping to a freezing -7C, MetService said.
Dunedin was the coldest main centre as it hit its lowest temperature this year of -4C, while Christchurch residents shivered through a low of -3.4C.
By 8am, the mercury was still at -3C in Queenstown and Timaru, while in the North Island Taupo residents brave enough to go outside were faced with an icy -4C.
Frosts blanketed much of the country.
With such conditions, police urged drivers not to take "careless risks".
"Driving in winter is not the same as driving in summer," national road policing manager Superintendent Steve Greally said.
"Extreme weather conditions such as ice, snow, fog and wet weather can hit quickly, so people need to be prepared ... and know how to handle the vehicle they are driving."
NZ Transport Agency's Greg Lazzaro said motorists should check forecasts and consider putting off or avoiding driving if the weather was bad.
They should also aim to drive during daylight hours because night conditions can bring multiple hazards.
"When you're on a wet, icy, or snowy road, it's important not to brake suddenly or to accelerate quickly, as you could aquaplane or skid," Greally said.
"People need to watch their following distances, make sure before they set out that their headlights and windscreen wipers are working, and check weather reports in alpine areas."
Hamner Forest in Canterbury highlighted how different conditions could be between summer and winter, the National Institute of Water and Atmospheric Research said.
Residents in the area had now experienced a 45.8C swing in temperatures this year, having hit a high of 38.4C on January 31 and now a low of -7.4C overnight.
Sean Jones living further south in Twizel in the Mackenzie Country runs a beef farm and the small Omahau Downs guest lodge.
Temperatures dropped to -7C in the area overnight, leading Jones to keep the fire running all night.
A white frost blanketed the ground around the farm and had even frozen water inside the pipes running to his lodge.
He's expecting guests tonight and needs to free up the pipes before they arrive.
But cold as it was overnight, Jones has seen worse. The temperature plunged to -20C in the area a couple of years ago, he said.
For those in Auckland, the night wasn't so extreme although the low of 5C was the city's equal coldest morning this year along with June 3.
Wellington by comparison was a balmy 9C overnight.
Fellow forecaster WeatherWatch said a large high rolling in from the Tasman Sea was responsible for locking cold air over the country.
"A southerly change followed by a large high is often the perfect recipe for cold nights and that's precisely what is happening," the forecaster said.
The consolation for Kiwis, however, is that sunny skies will blanket most of the country today.
Auckland is set for a top of 14C before dropping to an overnight low tonight of 8C.
Temperatures then warm to 16C and 17C on Thursday and Friday, although persistent rain is forecast for most of the North Island from tomorrow and could sour the mood.
Whangārei residents can expect a top of 16C today with tonight's forecast low of 12C about 5C higher than last night's low of 7C.
Hamilton and Tauranga can expect sunny tops of 13C today. The chilly frosts will continue in Hamilton where another overnight low of 1C tipped tonight before rain hits from tomorrow.
New Plymouth and Napier are both expecting sunny highs of 13C, while Wellington is set for a top of 11C with a chance of afternoon showers.
Christchurch is tipped to hit a sunny high of 11C after this morning's frosty start before the mercury again plunges below zero for an overnight low of -1C.
Dunedin is expecting a high of 11C and a low of 3C tonight.
Cloudy periods, chance shower from evening. Easterlies. High 16C, Low 12C
Auckland: Fine, then cloudy periods from afternoon. Easterlies. High 14C, Low 8C
Hamilton: Fine, with early frosts. Light winds High 13C, Low 1C
Tauranga: Fine. Southeast breezes. High 13C, Low 6C
Rotorua: Fine, with early frosts. Light winds. High 11C, Low 1C
New Plymouth: Fine. Southeast breezes turning northeast evening. High 12C, Low 4C
Napier: Mostly cloudy, becoming fine overnight. Southerlies gradually dying out. High 13C, Low 2C
Whanganui: Fine, early frosts possible. Light winds. High 14C, Low 1C
Wellington: Some morning cloud and chance shower, otherwise fine. High 11C, Low 6C
Nelson: Fine with a frosty start and light winds. High 12C, Low 3C
Christchurch: Fine with a frosty start. Northeast breezes developing morning. High 11C, Low -1C
Dunedin: Fine morning with inland frosts. High cloud from evening. Light winds. High 11C, Low 3C