The Desert Road might close again and 2m snow drifts on the Napier-Taupō Road are still being cleared, the New Zealand Transport Agency (NZTA) says.
Contractors and road crews have been working today to clear roads and restore phone and power to houses in the Taupō District and remote areas of Hawke's Bay.
About 400 homes across the two districts were still without power this evening after the weekend's snowstorm brought down about 200 power poles.
The Desert Road reopened at midday, after snow kept it closed all weekend, with drifts up to 1m accumulating.
Lines company Unison warned people to be vigilant and avoid broken lines buried under snow, after children were seen playing close to downed wires
It said it had visited all homes in the high country areas of Hawke's Bay and was confident it could restore power to most in a few days.
But for those in the Taupō area, it would take longer because the amount of snow and terrain made access difficult.
It would hold a meeting at midday tomorrow at the Rangaitaiki Tavern, where locals would be briefed on progress by representatives from Unison, Civil Defence and the council.
NZTA regional performance manager Mark Owen said the Desert Road might close again if it got too icy.
He said crews were working to clear the Napier-Taupō Road and were hopeful it would open tomorrow.
'Devastation right through'
Duncan Klaus - the owner of Rangitaiki Tavern, which is partway along the Napier-Taupō Road - said it would be "pet possum pie and pigtail soup" for those snowed-in around Hawke's Bay.
He said it was the weight of the snow on the lines that had pulled the power poles down.
"You get that weight on and then you get a bit of a breeze blowing and because there's quite a big area that will catch the wind when you take between pole and pole, and I guess that sort of swings the top of the pole over and then bang, there you go.
"We got no concrete poles here on our property but there's devastation right through, there's a lot of wires went across roads and across tracks, private roads and obviously a lot of wires brought down in those areas."
He said earlier today that the storm had brought down about 25-30 poles on Lochinver Station alone.
"There's wires down everywhere right through Landcorp, which is a big block," he said.
"Lochinver itself, right the way down through to Ōpepe, which is just south of Taupō on the Napier road still, there's trees and wires come down. It's pretty catastrophic really."
The clean-up would take longer than Unison was saying, Mr Klaus said.
"With all the poles down there's at least three weeks work out there repairing them, in the meantime I believe they're going to bring in some big gen-sets to put around the area," he said.
"That's sort of only the beginning too, I mean there's houses here where all the spouting's ripped off, and there's garages that have fallen in on a lot of homes actually."
Stock losses as shelters collapse
He said he believed there had been quite a few stock losses as well.
One farmer, Sarah McGough, said her farm had only lost one cow, but they had been without power since Saturday morning, and thankfully had a generator at her house.
She had been working in snow so heavy her dairy cows simply had not been able to move through it, she said.
"Well I'm five foot three and it was up to my hip, like I was just about bogged in it, I felt more worse off for the cows," she said.
"There are a couple that have calved with the circumstances and the weather."
She said the farm's calf sheds had collapsed under the weight of the snow.
"It's amazing, like, it's an eye-opener. It's a good little challenge."
Federated Farmers Hawke's Bay provincial president Will Foley said he was trying to get updates from as many farmers as possible to get an overall picture of the situation.
"The situation is quite isolated - it's just the north-western tip - but it's quite serious for those guys," he said.
"We haven't heard too much about livestock but the power's out so one of the issues is around dairy farmers and milking - so those guys are trying to get generators."
He estimated about 20 dairy farmers were affected.
Lambing had not begun in most of the region, but the heavy rain and very cold temperatures could have an effect on early lamb flocks in the southern part of Hawke's Bay, Mr Foley said.
Lines company Unison spokesman Danny Gough told Morning Report damage to the network was extensive and the worst he had seen in 10 years.
Unison had helicopters out assessing the damage, with some areas looking like "a bomb site", he said.
Extra crews were coming in to help, but it would be several days or even a week before power was restored.
The terrain and extent of the damage made it a challenging task, Mr Gough said.
Besides 1-2cm of snow expected to fall above 600m on the Napier-Taupo Road, and about the summit of Rimutaka Hill Road, MetService issued no further snowfall warnings.
State Highway 5 along the Napier-Taupō Road would remain closed.
A large section of State Highway 2 in eastern Bay of Plenty also remained closed this evening after a large slip.
State Highway 87 between Kyeburn and Outram was closed this morning but re-opened just after midday.
In Wellington, there were two minor collisions on State Highway 2 near Upper Hutt, which was also affected by black ice.
About 60km from Taupō in Upper Mohaka, heavy rain washed out a large section of the local road, leaving farmers stranded without power and phone.
Ice, including black ice, was affecting inland roads in South Canterbury, Otago, Southland, and even parts of the Nelson region, NZTA journey manager Lee Wright said.
Cold temperatures across wider New Zealand expected to last
Temperatures fell to -8°C in Alexandra and -6° in Queenstown overnight, and light snow fell in the Ranfurly-Naseby area this morning.
While Hawke's Bay was the worst hit, freezing temperatures created treacherous conditions on roads across the country.
MetService said there would be no reprieve from the cold yet with a high-pressure ridge coming across the country over the next few days.
It would likely bring fine weather to the South Island, but temperatures were likely to remain below zero.
It issued a severe weather watch for heavy rain and possible thunderstorms in Northland, with the system expected to drift across Auckland tomorrow.