SH35, at Waipiro between Ruatoria and Tolaga Bay, north of Gisborne, was also closed because of washed out approaches to a bridge.
The Antarctic blast was expected to continue and keep temperatures below freezing this evening and overnight, said New Zealand Transport Agency network operations manager Dave Bates.
"Extensive efforts have been made to re-open roads and clear snow, however roads will remain wet and it is likely that sheet ice and black ice patches will form making driving conditions treacherous overnight and tomorrow morning.''
People should stay at home until temperatures rose and ice began to thaw unless travel was essential, he said.
WeatherWatch.co.nz said there could be a lot of black ice about - especially in the South Island - as skies continued to clear.
Frosts, possibly severe, were expected in a number of regions.
Ice and snow could also pose serious problems around the central North Island and possibly the lower North Island, head weather analyst Philip Duncan said.
One last icy blast
The icy winter storm appears to have loosened its grip on parts of the country but forecasters are predicting one last blast with snow, hail and squalls pushing in from the south.
WeatherWatch.co.nz head weather analyst Philip Duncan said people should not be fooled if the sun was shining in their area.
The North Island was in for round two with a second pool of cloud, snow, hail and squalls pushing in from the south and southwest, he said.
Sleet fell in parts of west Auckland, with snow clouds clearly visible over the city - an extremely unusual sight for the region.
The heaviest snow in decades has fallen along the Kaimai Ranges, with heavy snow clearly seen above 500m and lighter snow estimated to have fallen to about 300m on Mt Te Aroha.
The next burst of energy is likely to be the last main one. It brought blizzards to Christchurch and other parts of Canterbury this morning and was now moving towards Wellington and southern Wairarapa, and in the west moving over Taranaki and up the west coast towards northern and central parts of the North Island.
Heavy snow continues to fall at Stratford, Taranaki, and WeatherWatch.co.nz says more is to come this afternoon before easing and clearing.
Heavy isolated hail storms are also expected right up into Auckland and beyond.
It snowed in parts of Wellington, down to sea level, but was isolated and not settling, Mr Duncan said.
The secondary burst could bring snow to the top of the Waitakeres during isolated squally showers, with a higher chance of snow on the Hunua Ranges to the south and the Coromandel ranges to the east.
However, conditions should ease for most places tonight - starting in the deep south then clearing northwards and by Wednesday relatively mild weather should return to most of the country, Mr Duncan said.
Melting snow gives way to traffic
The snow has begun to melt in and around Invercargill and some roads have reopened, including the road through to Queenstown, said Sergeant Brock Davis of Invercargill police.
There were no serious crashes in Southland, he said.
SH1 between Invercargill and Dunedin had reopen, as had SH94 between Te Anau to Milford, but SH93 between Mataura and Clinton remained closed.
Senior Sergeant Brian Benn, of Dunedin police, said a few people had "gone for a play'' in their cars and behaved stupidly but overall people had driven to the conditions.
In the North Island, the Rimutaka Hill road, north of Wellington, was closed but the Napier to Taupo Road reopened around lunchtime. The Desert Road was open this afternoon, Turangi police said.
Snow robs Cantabrians of power supply
Heavy snow cut power to more households and businesses in Christchurch and central Canterbury today.
By 1.30pm, almost 5000 customers across the Orion network region were without power.
Orion's commercial general manager Rob Jamieson said only minor network damage has been found at this stage, mostly to overhead lines which are fast to repair.
Inspector John Price says police have been responding to callouts across the city, and have been checking areas where power has been cut off.
"For some people this will be a stressful time - coming on top of earthquake damage and uncertainty. We urge people to check on their neighbours, friends and families - make sure they"re safe and warm, and offer assistance if you can."
Christchurch set for another surge
Snow is forecast to continue falling in Christchurch with another "surge of snow" expected until about mid afternoon.
MetService said another 10-20cm above 400 metres and 5-10cm down to sea level was expected from 9am to 3pm.
A foot of snow has already forced most workers to stay at home, closed Christchurch Airport and forced the cancelled of all elective surgery and outpatient clinics.
The heavy dumping of snow over night has prevented hospital staff getting to work.
But Burwood Hospital is operating as normal, both elective surgery and outpatient clinics will continue today.
A city's snow blanket is part of what is believed to be New Zealand's coldest weather event in 16 years.
Forecaster WeatherWatch said wind chill temperatures in Christchurch this morning plummeted to -9 Celsius, -6C in Dunedina, -5C in Wellington and -2C in Taupo.
MetService forecaster Paul Mallinson said New Zealand had not had a nationwide cold snap of this severity in 16 years.
"It's a real cold one, a 15-to-20-year outbreak ... The last time we remember snow getting to this low in Wellington is around 1995."
MetService has lifted heavy snowfall warnings for Fiordland, Southland, Otago, and the west of Nelson.
Snow falls in unusual places
Snow has also fallen in unusual parts of the country this morning, with the Bay of Plenty's Kaimai Ranges, Taupo and Taranaki all suffering from the wintry bite.
Rare snowfalls across NZ, none in Auckland - yet
WeatherWatch head analyst Philip Duncan said had been unconfirmed reports of snow flakes falling on Auckland's Mt Wellington.
He said reports of snow fall were coming in thick and fast this morning.
"We've had reports of snow in Lower Hutt and Wellington overnight and this morning. We've got reports of snow settling on the cars in Masterton for the last hour, snow at very lower levels at Lake Taupo and in Taupo itself, snow in Hawera, Stratford, Taranaki," Mr Duncan said
Mr Duncan said there had also been one unconfirmed report of snow near Raglan, in Waikato, however there had been very heavy hail in the region.
"This isn't the snow storm of the century ... but what makes this system different ... is the low snow level, which is sea level across much of southern and eastern South Island and to very low levels right across the lower North Island. This is a national event," Mr Duncan said.
Roads closed across NZ
The wild weather has closed roads around the country and many stranded motorists in the South Island.
About 220 stranded motorists, including families with young children, were sheltering in the Waitati Hall last night, after snow closed Dunedin's Northern Motorway and the Kilmog hill yesterday, the Otago Daily Times reported.
Snow ploughs cleared the road late last night, allowing traffic to move again.
Around 30 motorists were also temporarily trapped on the Devil's Staircase near Queenstown yesterday.
Police reported about 20 vehicles had slid off the road between Queenstown and Kingston. Queenstown Lakes District Council said the road remains closed.
Invercargill police reported attending eight car crashes between 12pm and 2pm yesterday, caused by drivers moving too fast for the conditions.
Senior Sergeant Dave Raynes, of Invercargill police, said many cars had left the road because of severe ice on State Highway 6, south of Lumsden to Kingston, 48km south of Queenstown.
