Freezing conditions in the North Island have closed roads - leaving trucks stranded overnight - and the southerly blast is also expected to disrupt ferry sailings.
In the central North Island seven trucks in Tongariro National Park have become stranded overnight.
They've just become stuck in the ice and snow as they tried to get up some of the inclines," police communications inspector Ken Climo said.
The trucks had headed up State Highway 49 between Waiouru and Ohakune before becoming stuck just south of Horopito.
Police were called by one of the truck drivers at 3am. The road was closed around 5am and will be reassessed later this morning.
Mr Climo said the trucks would have to wait until the road thawed enough for them to get going again.
The MetService yesterday issued heavy snow warnings for the central North Island and Canterbury plains with motorists told to check conditions before attempting the Desert Road.
By 6.30am today SH1 just north of Waiouru had been closed by a truck an trailer unit which jack-knifed and blocked both lanes.
Police in Taranaki issued a plea to motorists to take care this morning after icy roads led to three crashes overnight.
Bluebridge Cook Strait ferry spokeswoman Wendy Pannett said yesterday the service had cancelled two sailings due to rough seas as swells hit 9m.
One Bluebridge ship requested a tug to assist with berthing in the strong Wellington winds.
An Interislander spokesman said all its ferries had kept sailing, although there had been some delays.
Swells up to 12 metres were forecast for Saturday in the Cook Strait.
"It's going to be a bit lumpy for the next three days. If the sailing does go it'll be lively. I don't think they'll be selling many meat pies," regional harbourmaster Captain Mike Pryce told the Dominion Post.
Weather analyst Philip Duncan said the cold snap was set to continue until tomorrow as winter had "well and truly arrived early".
" It's like we haven't had an autumn.
"We are two months away from the coldest part of the year, so to see temperatures this low is certainly eyebrow-raising."
Southerlies were expected to continue chilling the North Island until at least Friday, possibly through to Sunday, he said.
In Canterbury temperatures struggled to reach more than 4degC yesterday while rain and sleet fell on Banks Peninsula.
Police said the weather may have contributed to a fatal crash near Invercargill yesterday as heavy hail created treacherous road conditions.
The South Island was likely to clear today although temperatures would remain low.
