Freezing temperatures have been recorded in parts of the country early this morning - with some areas dipping to a near teeth-chattering -10C.
Weather experts in the South Island say temperatures dropped to -10C at Mt Cook - while Tekapo has passed -8C.
Mackenzie Country Weather NZ recorded the temperatures about 6am and said Twizel was sitting at -3C early on.
However, it was thought the temperature could dip even lower later this morning, they said.
• Weather: Heavy overnight rain causes slips, flooding, road closures across Coromandel and Gisborne
• Weather warnings: Heavy rain, strong winds for Auckland; top of the North Island
• Weather: Heavy rainfall and snow in the south
• Weather: Fine conditions, but sub-zero temperatures on the forecast
"Twizel could get as low as -5C. Burke's Pass is around -6C."
Because of the frosty conditions, motorists are reminded to be careful while out and about on the roads early this morning, due to possible ice - particularly for those travelling on State Highway 8 and SH80.
Aucklanders are waking up to a mostly fine start to the working week. A temperature high of 18C and overnight low of 10C is forecast.
There will, however, be a few morning showers in the City of Sails, the MetService says.
Some rain in and around Northland - including in Kaitaia and Whāngārei - both have highs of up to 15C.
Anyone in Hamilton and Tauranga will be happy to see a whole lot of sun today; as will those in Taupō, New Plymouth and Palmerston North.
Rotorua will enjoy a day with the sunshine too - save for a few clouds and south-easterly winds.
Again in the South Island, chilly conditions are also forecast in Invercargill, which is expecting a high of -4C. Those in Dunedin will see a high of 0C and people in Queenstown will be in for a high of -4C.
Much of the South Island is forecast to get a great start to the week, with sunny weather expected in most parts except for Blenheim, which is in for some rain today. A cloudy day is on the cards for Christchurch.