Temps drop below zero in some places as winter blast hits South Island

Temperatures dropped below zero in some parts of the South Island overnight, as a polar blast brought frigid temperatures and snow.

The South Island continued to brace for a surge of winter weather, with several warnings for snowfall on roads and coastal swells in place.

Heavy road snowfall warnings are issued for Desert Road (SH1), Arthur's Pass (SH73), Porters Pass (SH73), and the Dunedin to Waitati Highway (SH1).

Hanmer Springs to Springs Junction (SH7) is now open but drivers are urged to drive to the conditions.

Fairlie to Twizel (SH008) and Lake Pukaki to Aoraki/Mount Cook (SH80) will be closed from 6pm. A decision will be made in the morning about when they'll reopen, a NZTA spokesperson said.

"This is because more snow flurries are expected overnight, and this combined with snow melt and freezing temperatures will likely mean extremely icy roads tonight."

According to RNZ, MetService said 15-25 centimetres of snow could accumulate above 500 metres elevation, meaning potential travel disruptions and possible damage to trees and powerlines.

Authorities are urged caution as road conditions remain slippery.

Lake Tekapo Volunteer Fire Brigade said it witnessed "a bit of chaos" on the roads last night.

"The Brigade responded to a grader that rolled off its transporter, and then other motorists being caught out with the snow."

Heavy snowfall coated parts of the South Island's most popular ski fields last night.

"All three of our mountains were blanketed by snow overnight". said Paul Anderson, NZSki CEO.

"Mt Hutt scored a massive 90cm dump, while The Remarkables and Coronet Peak each picked up around 15cm.

"With cold temperatures sticking around for the next few days, conditions are looking ideal for snowmaking as we gear up to open next weekend."

Heavy swell warnings were in place for the coast of Wellington (Cape Terawhiti to Turakirae Head) and Wairarapa (Turakirae Head to Mataikona).

Swells were expected to rise to 6 metres before easing tomorrow.

Large waves have caused travel disruptions for the Cook Strait ferry services.

The Interislander cancelled all passenger sailings for today, due to "very rough sea conditions".

Metservice said chilly temperatures would continue for the rest of the weekend.

The lowest temperature recorded on Friday night at -2.4 °C at Lumsden and Tekapo. The rest of the South Island failed to reach above 10 °C.

In Christchurch, temperatures are forecast to reach just 8 °C, with patchy rain and a chill southerly breeze.

Invercargill and Dunedin are expected to stay cold, with highs of 6-7 °C and showers across the weekend.

Looking ahead to the rest of the weekend, Auckland, Northland and Coromandel are likely to experience showers, with possible thunderstorms and hail, clearing around Auckland and the Coromandel Peninsula by late afternoon.

Bay of Plenty and Taupo can expect partly cloudy conditions with several showers expected to clear later today. Gisborne, Hawkes Bay and Wairarapa can expect scattered rain this morning, which will likely clear this afternoon.

Waikato to Wellington can expect showers clearing north of Taranaki and Taihape this morning, and possible snow for the Desert Road.

Fine conditions are expected in Western Marlborough, Nelson and Buller through to Westland and Fiordland.