South Island motorists are being told to stay home as snow and ice leaves roads too lethal to drive on.
And the news isn't any better for those planning to cross Cook Strait today after KiwiRail cancelled sailings earlier than planned when the weather - 7m high waves are expected - deteriorated ahead of schedule.
Interislander general manager of operations Mark Thompson said today's 2.45pm and 5pm sailings from Wellington and the 6.45pm sailing from Picton had been cancelled.
Sailings were expected to resume on Friday morning, depending on the weather, he said.
The latest disruption comes as the snow forecast for the North Island worsens and the MetService extends heavy snow warnings to include the Manawatu ranges and Taumarunui as the "significant" winter storm bears down on the centre of the country.
Even the north of the country looks as if it won't escape the approaching wild weather, with howling gales threatening to lash Auckland and Northland tomorrow.
The New Zealand Transport Agency says South Island roads are in a treacherous state and the safest place for vehicles is in the garage. It's also worried about travel through the central North Island, with heavy snow expected to fall on the Napier-Taupo Rd and Desert Rd in coming hours.
"If you are able to, postpone your journey," said agency journey manager Lee Wright.
"In many places snow is lying on top of ice, making driving extremely dangerous."
SH1 into Dunedin is closed because of snow on ice.
Nearly a dozen ice-related crashes have been reported in Otago and Southland since 1am.
Six crashes happened in Dunedin between 7am and 9.30am.
Those intending to travel through the Central Plateau were asked to delay their journey until Friday.
The agency is advising anyone daring to venture out to check the NZTA website and map, which show area warnings and highway closures.
This morning MetService warned that the coming days would be especially wild, when damaging gales, heavy rain and snow could lead to widespread disruption to travel, flooding and downed trees and lifted roofs.
Snow, which was expected to fall down to 100m across the far south today, came down to sea level in Dunedin. Flurries are blowing across central Christchurch.
A significant amount of snow was also expected to fall across the Central Plateau, Hawke's Bay ranges and Wellington region as the cold air invades the North Island.
The first snow had started to fall on the Rimutaka Hill Rd mid-morning but the highway connecting the capital to Masterton remained open.
"The combination of heavy rain, snow and strong winds is expected to cause widespread disruption to transport, especially about higher roads, [and] could lead to localised flooding and slips," said the MetService.
"Also, winds of this strength can cause damage to trees, powerlines and unsecured roofs and structures and make driving hazardous."
Snow is now falling heavily south of Waiouru. The Desert Rd was closed earlier today after a truck rolled on ice.
Gales were due to hit the centre of the country from tonight with winds of up to 140km/h, or more especially over Wellington.
An enormous amount of rain is expected across the lower half of the North Island, where up to 150mm is set to fall in the ranges and 100mm in lower-lying areas of Wairarapa and Wellington.
On top of this giant swells are set to pound southern and eastern coastlines of the North Island. The MetService is warning flooding is possible.
ROAD SNOW WARNINGS
The MetService's latest road snow warnings, valid until 11am Thursday. Note that the measurements reflect how much snow is forecast, and don't take account of snow already on the roads.
Snow to affect the road at times until early Friday, with 3-8cm accumulating around higher parts.
Snow at times until Friday morning, 15 - 25cm accumulating in higher parts of the road. (WeatherWatch has said there could be up to 50cm of snow by Friday, with snow drifts up to a metre in exposed places.)
RIMUTAKA HILL ROAD
Snow at times until Thursday 12pm. 10 - 15cm accumulating near the summit.
Snow until Thursday afternoon.
Snow warning lifted as further significant snowfalls unlikely.
Snow showers at times until Thursday afternoon. 15 - 25cm accumulating about the higher parts of the road.
Light snow showers could affect the road until Thursday morning.
A few snow showers possible south of Lake Gunn until Thursday morning.
DUNEDIN TO WAITATI HIGHWAY
Snow showers could affect the summit tonight, with 1 - 2cm accumulating.