Kiwis have woken to freezing conditions on Tuesday morning with temperatures dropping as low as -6C in some areas.
"Temperatures this morning were the coldest of the year for parts of the country with even some people reporting their first frost - which is very late in the season," WeatherWatch said.
As of 7:30am, MetService said areas of the Canterbury High Country remained well in the negatives - Omarama being the coldest at -6.3C. Invercargill and Timaru also dropped to -1C.
Further inland, Queenstown fell to an overnight low of -3C.
It was cold in the North Island too with many areas dropping to the low single digits, according to MetService. Hamilton plummeted to 0.9C, Rotorua 2.2C and Auckland 6.7C.
"It's a cold one across the country this morning and there are a few more cold nights to come. Brrr," MetService said.
The Southern Hemisphere's shortest day, or winter solstice, was also happening on Tuesday - which signals the start of the astronomical winter, Newshub weather presenter Heather Keats explained.
"Winter started on June 1 for most of us [but] if you run by the astronomical seasons, we do it on the winter solstice, the summer solstice and then the equinoxes - so today marks the beginning of winter," she told AM.
Looking ahead to Wednesday, it's expected to be another cold start to the day. MetService said Auckland would see a low of 5C, Hamilton 0C, Wellington 4C, Christchurch -2C and Dunedin 2C.
"Frosts will be widespread across inland parts of the South Island tonight as powerful high pressure slowly moves in with clearer skies, lighter winds - and a gentle southerly flow," WeatherWatch said on Tuesday.
"Coldest weather will be over the South Island tonight with the frost forecaster at RuralWeather.co.nz showing heavy frosts across a number of regions and temperatures inland dropping below -4C."
But with the cold temperatures comes mostly settled weather, with a ridge of high pressure dominating New Zealand through to Thursday.
"The high should move eastwards on Friday and northerly winds develop over New Zealand. A front, preceded by strong northerlies, is forecast to move onto the South Island from the Tasman Sea on Saturday, bringing a period of heavy rain to the West Coast," MetService said in its severe weather outlook.
