Vehicles stranded on the Lindis Pass are being rescued early on Saturday, so that State Highway 8 can re-open after it snowed overnight.

A polar blast swept through the lower South Island on Friday, leaving up to a metre of snow. However, fears of an extreme cold snap had not eventuated, despite chilly temperatures around the motu.

The country went into the latter part of the week with almost two dozen weather warnings in place, but rain eased on Friday in Tāupo and the Bay of Plenty, and the South Island avoided heavy snowfall.

On Saturday, a strong wind watch was issued for the Chatham Islands through to Sunday due to a nearby deep low, bringing northerly gales.

MetService meterologist Sylvia Martino told RNZ Dunedin Airport and Takapō took out the chilliest spots, at minus five overnight, while Christchurch dropped to minus one.

Takapō on Thursday after an overnight snowfall. Photo: Supplied / Tanja Clauberg

Snow has closed parts of State Highway 85 in Otago, State Highway 80 between Lake Pukaki and Aoraki/Mount Cook and State Highway 8 between Fairlie and Twizel.

Crews had been working through the night on Friday to clear roads and council contractors in the Clutha District were out on Saturday to assess the situation.

MetService had issued an orange-level heavy snow warning for inland Canterbury, from the Rakaia River southwards, overnight. A heavy snow watch remained for inland areas of Canterbury and Marlborough between the Rakaia River and Ward until later on Saturday morning.

A warning was also in place for State Highway 1 on the central North Island's Desert Road, with one to three centimetres of snow to accumulate above 800 metres.

Meanwhile, the Wellington Region Emergency Management Office is warning people to take extra care along the region's coastline with heavy swells forecast over the weekend.

A warning is in place in Wellington, from Cape Terawhiti to Turakirae Head, and in the Wairarapa, from Turakirae Head to Mataikona, through to early Sunday morning.

Cook Strait ferries have been cancelled this weekend due to forecast 6m swells.

Interislander has canned all passenger sailings for Saturday due to the conditions.

"All passengers are being moved to alternative sailings," it said on its website.

Cook Strait ferries are being cancelled this weekend due to forecast swells. Photo: Supplied

Bluebridge had also cancelled all Saturday sailings, and one in the early hours of Sunday morning.

"We are monitoring the situation closely, and if further sailings are impacted, we will notify you via text and email at the earliest opportunity," the operator told customers.

The MetService said waves could reach swells of 6m on Saturday, with a warning lasting to Sunday morning.

The Wellington Region Emergency Management Office's regional manager, Dan Neely, said it could bring flooding and debris onto roads.

He added that drivers and walkers on coastal roads, as well as surfers, divers and fishers, should take extra care.