Icy roads as temperatures drop in cold snap

Icy roads are causing problems in parts of the South Island with vehicles losing control on ice in Dunedin and one hitting the side of a bridge.

There was ice on Stuart Street in the city and on bridges south of Dunedin on State Highway 1, but by mid-morning SH1 from from Waitati to Dunedin had reopened.

A dozen roads in Dunedin city that were closed earlier this morning have now reopened and the council's gritting trucks have been out working on the network.

Arterial roads through the city had reopened and by midday only Mount Cargill and Stedman Road remained closed.

Ice on the runway has delayed flights in and out of Dunedin airport until further notice.

Air New Zealand said four flights to and from Auckland and Christchurch were cancelled, and other services have been delayed.

Snow fell overnight in the Alpine passes in the South Island as well as the Desert Road in the central North Island.

In Christchurch, Port Hills and Banks Peninsula had snowfall.

State Highway 75 from Little River to Duvauchelle remains closed.

At midday, MetService meteorologist April Clark said the cold front was moving over the North Island, with snow expected from 500-600m over the lower and central North Island.

"Snow affecting the upper South Island, including the higher suburbs of Christchurch, is on the easing trend, with showers and snow set to gradually clear," she said in a statement.

"As for the North Island, showers and bitter conditions are expected throughout the day, with snow lowering to 5-600m over southern and central regions. Road Snow Warnings are out for the Remutaka Hill Road, Desert Road and Napier-Taupo Road this afternoon and evening."

Settled weather is forecast after the cold front sweeps through before more unsettled weather forecast for the weekend.

Clark said the clear skies will mean cold temperatures in the South Island with Queenstown expected to drop to -5C on Friday, with the cold temperatures set to hit the North Island on Saturday morning when it is forecast to drop to -3C in Masterton.

"The Women's World Cup quarter finals in Wellington and Auckland on Friday have picked their weather window well; with today's wet weather forecast to clear by both kick-offs tomorrow. However, layers will be the key, even if the packed stadiums will help raise the cool temperatures by a degree or two."

Waka Kotahi Mark Owen told Morning Report snow and ice have closed two highways out of Dunedin this morning.

"For other roads that are open we just advise extreme caution, black ice is really hard to detect."

Black ice was typically caused when it rained and then it froze and was very hard to detect and dangerous to drive on, he said.

Snow was making some South Island travel difficult, and at midday SH73 through Arthur's Pass and SH87 from Outram to Middlemarch were still closed.

In the North Island, the Desert Road which was closed due to snow, has now reopened.

Owen said people should check before they travelled because other roads may be closed as the day progresses.

Tasman District Council earlier said a number of vehicles were stuck on the Hope Saddle due to snow. It warned people to check for road closures if they were travelling in the region today.

In the North Island, the Desert Road was closed earlier today and Owen said the Remutaka Hill Road may also be affected depending on how far down the snow came.

Things could change rapidly depending on how the bad weather moved north but there will definitely be cold temperatures over the next 48 hours and motorists should drive with caution, he said.

MetService meteorologist Andrew James this morning said temperatures had plummeted overnight, reaching -6C at Tekapo, and a combination of cold temperatures and wet roads has led to icy roads.

That wet weather from the south was moving across the lower North Island making for a wet start to the day in Wellington.

At 1.30pm road snowfall warnings were in place for Napier-Taupō Road (SH5), the Desert Road (SH1) and Remutaka Hill Road (SH2), while the warnings that had been in place for several highways and passes in the South Island had been lifted.

James said cold temperatures would last at least until the weekend. "The next couple of nights are going to be the coldest," he said.