Rockfalls and snow have closed main thoroughfares while motorists in the South Island have been left stranded overnight in their cars after a freezing start to the long weekend.
Two people were stuck in their car on a remote section of State Highway 8 between Burkes Pass and Kimbell on the edge of the Mackenzie country.
Police were called out shortly after 2.30am on Saturday after the vehicle was stranded in the middle of the road, unable to move because of snow.
Officers urged the pair to stay put, and they have since been rescued.
Elsewhere, a vehicle was stranded for more than four hours in a snow ditch on the highway between Geraldine and Fairlie in Canterbury, before being helped out by passers-by just after 7am on Saturday.
The strandings came as Canterbury bore the brunt of the bad weather that has lashed the nation overnight Friday and early on Saturday.
By the afternoon that pelted the South Island with wind, snow and rain for much of the day hit Wellington too, Metservice metereologist Tamara Vuksa said.
Wind speeds picked up sharply with an average wind speed of 75kmh and gusts of 100kmh recorded around 4pm at Wellington Airport.
It was a sharp increase on the day's average wind speed of 20kmh.
And with the wind came rain with 7.4mm of rain recorded at a Wellington Airport weather station since 1.30pm.
Vuksa said the rain and wind would continue throughout the night in Wellington but was likely to ease off tomorrow.
In the South Island, Arthur's Pass and Lewis Pass were closed, severing the region's links with the West Coast, amid whiteout conditions and flood warnings across the country.
Rain of up to 100mm was expected to fall across the Canterbury Plains on Saturday, triggering fears of significant flooding in Christchurch and across the region, forecasters say.
Gale force winds are also likely to batter large parts of the country, from Hawkes Bay and the Wairarapa down to the Kaikoura coast and Banks Peninsula, with warnings that power lines may be damaged and travel disrupted.
Areas around Lake Tekapo were carpeted with a thick blanket of snow, while people in Oxford near Christchurch also woke up on Saturday to find their sections covered.
But the snow created an "exceptional" first day for up to 150 skiers who visited Happy Valley ski field visitors on Saturday.
The Mt Ruapehu ski spot experienced real snow on its opening day according to Whakapapa General Manager Jono Dean.
"We don't normally get natural snow fall and are completely dependent on the snow factory. We have been very lucky that mother nature delivered snow overnight"
More snow is likely over high ground on Saturday, with up to 10cm forecast above 600m in the Lewis Pass and similar amounts for Porters Pass, down to 400m.
Arthur's Pass to Springfield was closed from late on Friday, the NZ Transport Agency said, while Lewis Pass was shut from 10am on Saturday between the Hanmer Springs turnoff and Springs Junction.
Both alpine routes have since reopened.
At around the same time State Highway 1 was closed south of Kaikōura due to rockfall risk, triggered by the rain and winter weather hitting the coastline.
The driver of one car suffered minor injuries and the car's windscreen was damaged when it was struck by falling debris around 1:30pm.
The closure is between Peketa and Oaro and along with the snow-covered inland road to Waiau (Route 70) will be reassessed Sunday morning 9 am.
Motorists are advised to use the Lewis Pass road as the route south from Picton or north to Picton overnight.
The Desert Road is also expected to get snow overnight into Sunday, with warnings of delays and potential road closures across the weekend.
Police were unable to say how many call-outs they have received due to the weather, but the fire service in Canterbury said they had had 40 weather-related calls since 9pm on Friday, most about leaking roofs and two over flooded garages.
Downed powerlines have also caused some damage, Fire and Emergency NZ manager Andrew Norris said, with most of the issues in Rangiora, Woodend and Kaiapoi to the north of Christchurch, with some minor damage from the storm.
Storm damage cut power to 34 homes in Lake Coleridge, in central Canterbury, since about 7.15am, according to utility provider Orion.
A further 187 were without power but have had it restored throughout the morning. The final 23 homes were expected to be reconnected by 7:30pm on Saturday evening.
In Christchurch, 75mm of rain overnight into Saturday caused surface flooding in many parts of the city, forcing the closure of a number of roads and sports events to be cancelled.
City council contractors have been out checking conditions, with a streets maintenance manager urging people to slow down and drive carefully.
One resident on Tainui St in Somerfield said floodwaters from the streets had washed under her home, while in Kaiapoi waters have reached almost 30cm on some streets.
MORE COLD WEATHER AHEAD
The wintry weather is expected to remain well into next week.
Forecasters Blue Skies Weather said strong and very cold weather will push in from the south into Sunday, before a second low pressure system on Tuesday brings more heavy rain and snow into Wednesday.
A spokesman said: "There is still some uncertainty, but a significant chance of 30-50cm of snow accumulating above 300m on Wednesday, and greater amounts above 600m.
"Snow showers will clear later on Thursday but temperatures will remain very cold for several days as southwesterly airflow eases only slowly so snow drifts could be slow to clear."