Waka Kotahi Transport Agency is urging people to be careful on the road as unsettled weather makes its way across the South Island in time for the start of the school holidays.
MetService is forecasting severe conditions, which can make driving hazardous, while several heavy snow and rain warnings are already in place.
A heavy snow warning is in place for the Canterbury High Country south of the Rangitata River where 5-10cm of snow is expected to fall down to 400 metres.
The snow is expected to contribute to travel delays while MetService has warned trees, powerlines and livestock in the area could all be at risk.
Heavy snowfall has left some holidaymakers stranded, after alpine passes through the Mackenzie country and Central Otago closed due to snow.
Christchurch resident Megan Brown said she and her friends had been stranded in Lake Ohau in the Mackenzie basin during an overnight stop off.
She said the group was en route to Queenstown, but are unable to travel through the Lindis Pass due to not having any chains in their vehicles.
Queenstown Lakes District Council says there is also an underlying layer of black ice on the Crown Range Road.
Waka Kotahi said most alpine passes had reopened by this afternoon.
Motorists have been urged to use the alternative route through Kawarau Gorge but they are warned to be cautious as this route is also affected by snow.
The council is expected to provide an update on the condition of the Crown Range Road and Lindis Pass at 10am.
People are being reminded to carry chains wherever they're travelling in the district today.
There are heavy rain warnings in place for many parts of the North Island and western South Island.
On the South Island's West Coast, a heavy rain warning is in place for the ranges of Westland south of Otira with 150-230mm of rainfall expected between now and Saturday evening.
MetService has warned the heavy rain may lead to surface flooding, slips and hazardous driving conditions.
Meanwhile, Tasman west of Motueka, Gisborne, Bay of Plenty and Mount Taranaki are also under heavy rain warnings.
"The key thing is the weather is very unpredictable." - Waka Kotahi journey manager, Tresca Forrester
Waka Kotahi journey manager for Canterbury and the West Coast Tresca Forrester told Morning Report the South Island's highways are being hit with some unpredictable weather.
"We've got a system coming through today and then more snow is forecast tomorrow on Saturday through the high country in Canterbury and we're expecting some again through the Mackenzie (District) and Central Otago but we've also got rain and a new system moving in on Monday next week.
"The key thing is the weather is very unpredictable, a lot of people are going to be getting on the road in the next 24-48 hours and over the next week we are just urging people to allow plenty of time to take extra care and constantly check the road and weather conditions before they head away," Forrester said.
She said crews were prepared to handle any issues, and closed roads allowed for snow to be plowed and cleared quicker.
She urged motorists travelling to the lower South Island to carry chains as many of the roads in the area are covered in ice if not snow, particularly on alpine passes.
With many people expected to travel to Dunedin for the All Blacks test match against Ireland, Forrester advised those heading to the game from Christchurch to stick to the State Highway 1 route along the East Coast.
Ski fields forced to close
South Island ski fields are welcoming a fresh snow dump ahead of the school holidays.
In the Queenstown Lakes district, Cardrona Alpine Resort, the Remarkables and Treble Cone ski areas were closed due to heavy snow and blizzard conditions in some areas.
Coronet Peak opened but said all vehicles travelling up the mountain needed chains.
Cardrona and Treble Cone experiences general manager Laura Hedley said it was a great snow dump.
"For Cardrona, we're forecasting for about 30 centimetres and then (Treble Cone), a wee bit more.
"The temperatures fluctuating a little bit at the moment. But it has snowed down in Wānaka so there will be some nice, cold, fluffy stuff up the hill."
It was a great start to the holidays after a less than promising lead up to the ski season, she said.
"It was definitely a warm May. We were standing on top of the hill with not much if any snow on the hill, and now we're up there we've got all the runs open, all the lifts open.
"Our team is just absolutely stoked and the guests so far, I think, have had a great time."
She hoped to open for the first day of the school holidays depending on the conditions.