Heavy snow and ice on the roads has closed highways across the South Island, while dozens of homes are without power in South Otago.
Meanwhile a thunderstorm watch is in place for Waitomo, Taranaki, Kapiti-Horowhenua, Marlborough, Nelson and Buller, with a moderate risk of winds in excess of 110km/hr, heavy rain, hail and possible small tornadoes.
The storms will pass through the Buller and Nelson regions this morning and early afternoon and pass up through the North Island after midday.
Severe gales up to 120kmh in exposed areas are also forecast about of central Hawkes Bay and the Tararua district this afternoon and evening, and in areas of the Catlins, Clutha and Dunedin from this evening through until tomorrow morning.
MetService forecasts the heavy snow which has fallen to low levels in Buller, Westland, Fiordland, Southland and Clutha overnight, will ease today.
Further heavy snow is expected in Westland north of Mount Cook and Buller this morning with another 10cm accumulating above 400 metres. In Clutha, Southland and Fiordland snow showers are expected above 200 metres today, although the snow level should rise to 400 metres this evening.
Another 10cm to 15cm could also accumulate in Clutha, Southland and Fiordland south of Te Anau.
MetService warned the large snow accumulations could damage trees, powerlines and weak structures.
A PowerNet spokesperson told the Otago Daily Times about 1700 customers were affected by outages or interruptions in South Otago and Southland this morning.
Most customers had power restored to their homes and businesses by 9am this morning, while 38 residents in the Slopedown area near Clinton remain without power.
The wider Clinton area, Lawrence and Conical Hill had power cuts, with Ohai, Edendale, and Riverton facing interruptions to their power supplies
The spokesperson said the problems were caused by heavy snow loading, outages due to flying debris and one vehicle accident.
State Highway 73 from Arthur's Pass to Otira, SH87 Outram to Kyeburn, SH6 Kohatu Junction To Kawatiri Junction, SH 6 Kawatiri Junction To Blenheim, SH 7 Reefton Saddle, SH93 from Clinton to Mataura, SH7 Hanmer turn-off to Springs Junction (Lewis Pass), SH94 Te Anau to Milford Sound (Knobs Flat to Milford Sound) are all closed due to snow.
Vehicle restrictions are all placed on several other South Island state highways due to heavy snow and ice. Updates on road closures can be found here.
In the North Island, the Desert Road has reopened this morning as conditions ease.
Black ice is also plaguing roads around the lower South Island.
The Queenstown Lakes District Council said main routes around the district have ice on the roads and have been gritted. The Crown Range is open, but chains are required and towing vehicles are prohibited.
The Fire Service said there had been several minor accidents in Dunedin overnight due to ice on the roads. Police are urging motorists to stay off the roads unless necessary.
A man is in hospital with serious head injuries after his car hit a power pole in central Dunedin overnight.
Police said the man's car hit black ice and smashed into the power pole on Macglaggan St at 3.40am.
Just after 7am a car slid into two other vehicles at the corner of Smith St and York Place.
Some schools in Dunedin opened at the later time of 10am due to the conditions in the city, while Lee Stream School is closed for the day.
Buses are still running in the city although light snow started to fall again in the hill suburbs at 7.30am.
Two flights haven been cancelled at Dunedin International Airport this morning.
Apart from Danseys Pass, all roads within Central Otago remain open.
The Clutha District Council said roads in the district were affected by snow and ice, particularly in the Slopedown area south of Clinton, the Owaka Valley and in the Catlins south of Owaka.
Nelson police are also advising motorists take extreme care on the region's roads, due to icy, particularly on bridges.
- Herald Online, Otago Daily Times