Motorists are being urged to plan ahead and in some areas only travel if they need to, with the wild weather far from over.
Snow has settled in parts of Canterbury and is widespread in Otago and Southland, with a major winter chill gripping the south of the South Island.
Metservice said the storm was a "significant weather event" with heavy rain, snow and strong winds causing widespread disruption to transport as it moved from the south towards Wellington and the central North Island.
Wellington Airport says Air New Zealand regional flights have resumed, but passengers can still expect some disruptions. There were numerous flight cancellations and delays at other airports in the South Island earlier today.
The snow and ice has closed about a dozen South Island roads and highways today.
Motorists have been advised to take extra care and chains must be used in the alpine passes, some of which have been closed for the night.
Access in and out of Kaikoura has been cut off until 7am.
More than a dozen stranded travellers are staying at the Mount Lyford Lodge tonight and a number of campervans have had to be towed in.
State Highway 1 south of the town is also closed overnight, with the Transport Agency saying coastal swells are the biggest concern along that road.
Other state highways around the South Island will also remain closed overnight, because of the weather conditions.
They include both Arthur's Pass and the Lewis Pass.
Drivers are being urged to plan ahead, and only travel if they need to.
SH1 in the Desert Road remains closed after a truck crashed and flipped onto its side.
NZTA regional transport systems manager Mark Owen said crews were on standby as the cold snap moved north.
He said motorists should avoid travel if possible, with the forecast for tomorrow for the lower North Island, particularly Wellington, not looking good.
"There's certainly some heavy rainfall and high winds predicted.
"So really advising people just to sort of plan ahead and think about what the alternatives are if they can't travel."
Ferry sailings have been cancelled earlier than expected with the Interislander's 14.45 and 17.00 sailings from Wellington now not going ahead.
The Interislander's final scheduled sailing had been the 5pm from Wellington and 6.45pm from Picton.
The service has no scheduled sailings tomorrow as swells of up to 7m and winds of 120km/h have been forecast for the Cook Strait.
More snow, rain and gales to come
MetService said the there would be more snow, severe southerlies and rain to come in the next 36 hours in the centre of the country.
Significant rainfalls are expected in Wairarapa, Wellington, Kāpiti and further north with up to 10cm predicted in low lying areas and more in the hills.
Wind chill keeps "feels like" max temps in the single digits 2day and 2moro. Blue/white areas = sub 0 effective temps. pic.twitter.com/hilkFhZ4Ui— NIWA Weather (@NiwaWeather) July 12, 2017
Metservice meteorologist Angus Hines said the snow would start to ease in the lower South Island in the next few days, but the area could get some very icy mornings.
Wind tonight is predicted to limit the frosts, but after that still weather and lingering cold temperatures could bring heavy frosts.
The central part of the country, from Marlborough through to Taranaki, will be battered by powerful southerly gales from tonight to tomorrow night with gusts up to 140km/h in Wellington that could damage trees, roofs, powerlines.
The Fire Service said strong winds were lifting roofs and flinging trampolines in Wellington and Porirua late this afternoon.
The Wellington City Council was asking residents to check their drains in preparation for heavy rain forecast in the city overnight and tomorrow.
More snow is forecast to fall until tomorrow afternoon in inland Canterbury and Kaikōura, with up to 30cm above 400m, and the central North Island high country to get 10cm at the same altitude.