Wednesday morning may be the coldest so far this year as temperatures drop well below freezing in parts of the South Island.
Hot water bottles and extra blankets were necessary last night as minus temperatures set in as low as -6C in the Mackenzie Region and Ranfurly, bringing widespread frosts to both islands.
Some of the coldest overnight lows were also felt in Tekapo, which fell to -5.3C, Clyde and Alexandra on -5C, Cromwell -4.8C and Gore -4.2.
Auckland was a touch less chilly with an overnight low of 4.2C and a frosty start of 4.8C this morning.
Sunshine and clear skies will stick around today, but icy roads conditions will be a concern this morning for inland areas.
Temperatures will stay well below average for this time of year for the rest of the day as well.
In the deep south road warnings for ice are in place across inland Otago and motorists are being warned to take extra care as "freezing fog" takes hold in some places.
Queenstown Lakes District Council this morning said freezing fog was providing an extra hazard in places this morning including in Aspiring Rd and Glendhu Bay in Wanaka, plus the Cromwell basin.
"Sharp frosts everywhere so, even if the roads look dry, there's a risk of ice especially in the usual hot [cold?] spots through shaded areas and over bridges."
The QLDC's roading crew highlighted the Kawarau Gorge, Gibbston Valley, Arthur's Point, Fernhill, Glenorchy and Alexandra and Ranfurly areas as worthy of special attention.
Central Otago District Council said there was another "hard frost" across its roading network with patches of freezing fog in places.
Temperatures in Central Otago were sitting around -4C as of 6.30am.
There was a high risk of ice and caution was advised particularly in damp areas, bridges, hill sections and shaded areas.
The NZ Transport Agency has also warned of delays in Auckland, with roadworks on Constellation Dr which are reducing lanes and slowing traffic flow on State Highway 18.
Today's forecast high is 15C in Whangārei and the coolest temperatures are again expected in Otago and Southland where 6C - 9C is forecast throughout the day and a freezing -4C is predicted in Invercargill overnight.
Later in the day, the sun will give way to cloud over the lower North Island and Gisborne may get a few morning and early afternoon showers as well.
A near identical copy of today's weather is expected tomorrow, but an area of low pressure in the Tasman Sea that is tracking towards the North Island may bring a wet Queen's Birthday weekend to parts of the country.
Whangārei: Fine. Southerly breezes. High 15C / Low 6C.
Auckland: Fine, early frosts inland. Light southerlies. High 14C / Low 6C.
Tauranga: Fine. Southerly breezes. High 15C / Low 4C.
Hamilton: Fine with early frosts. Light winds. High 13C / Low -1C.
New Plymouth: Fine apart from some morning cloud. Light southeasterlies. High 13C / Low 4C.
Napier: Mostly sunny. Southwesterlies. High 14C / Low 4C.
Wellington: A few morning showers then fine spells increasing. Southerlies. High 11C / Low 6C.
Nelson: A crisp, clear day with early frosts and light winds. High 12C / Low 2C.
Christchurch: Few early showers, then increasing fine spells. Light winds. High 10C / Low -1C.
Dunedin: Fine apart from morning and evening cloud. Light winds. High 9C / Low 3C.
- Additional reporting Otago Daily Times