A mammoth effort is under way to clear the Lindis Pass of more than a metre of snow.

A number of alpine passes in the South Island were closed after a dump of heavy snow over the weekend.

An NZME photojournalist at the scene says 1.5 metres of snow has fallen on the summit of the Lindis Pass over the last few days.

Contractors are doing everything they can to get the road open, they said.

Crews are working on both sides using graders and tractors to clear the large amount of snow to allow the road to open.

Graders were being used to clear the snow on the Lindis Pass on Monday morning. Photo / George Heard

A spokesperson for Waka Kotahi NZ Transport Agency said the road will remain closed overnight with an update expected at 10am on Tuesday.

A mammoth effort is under way to clear the Lindis Pass of more than a metre of snow. Photo / George Heard

Meanwhile, an Emergency Operations Centre (EOC) has been stood up in Westport as the area braces for more severe weather overnight.

A mammoth effort is currently underway on the Lindis Pass to clear over 1.5m of snow. Photo / George Heard

A spokesperson for Buller Emergency Management said current forecasting and modelling shows they could have a similar night to Sunday with rain, wind and high sea swells.

Residents in northern Buller whose properties have been impacted by this morning's sea surges are strongly encouraged to self-evacuate to friends or families on higher ground.

Flooding in Buller on the West Coast on Monday. Photo / Supplied

An Emergency Operations Centre (EOC) has been stood up in Westport as the area braces for more severe weather overnight. Photo / Supplied

"We are working with our community coordinators on assessing the situation, and
preparing our communities for further weather coming in tonight," said Mayor Jamie Cleine said.

People are advised to take bedding, water, food, medication, warm clothes and to remember their pets.

Roads to stay closed

The Buller Gorge and SH94 Te Anau to Milford are also expected to remain closed overnight.

The gorge is closed due to a slip and the NZTA is reporting avalanche activity on SH94.

The Arthurs, Burkes, Haast and Lindis passes were all closed on Monday because of snow or ice.

The Arthurs and Burkes passes reopened at about 1.30pm.

And large waves have been reported at the Greymouth Aerodrome in Blaketown this morning.

SH67 Granity to Mokihinui Rd was closed due to sea debris over the road but has since reopened.

The Ministry of Education says 12 schools across the country have closed as a result of the severe weather.

In Canterbury, Aoraki Mt Cook School has shut while seven in the Otago and Southland regions have also closed – they are Makarora School, Glenorchy School, Mt Aspiring College, Te Kur or Take Kārara, Wanaka Primary School, Holy Family School and Hāwea Flat School.

Meanwhile, weather warnings are still in place for parts of the South Island.

A severe thunderstorm watch is in force for Nelson, Buller, Westland and the Canterbury High Country until 4pm.

MetService is warning from western Tasman to the glaciers of Westland, there is a risk some thunderstorms may become severe until this afternoon.

More snow fell overnight in Wanaka as a cold snap hits the country. Photo / George Heard

The thunderstorms could bring large hail greater than 20mm in diameter as well as damaging winds gusting at more than 110 km/h.

An orange heavy rain warning is in place for Westland south of Otira until noon and a strong wind warning has been issued for Marlborough, Westland, Buller and the Canterbury High Country.

It comes after snow blanketed parts of Central Otago yesterday, bringing joy to the region's ski fields, with Cardrona ski field opening early and other southern mountains set to follow suit in the coming days.

A number of highways in the South Island had been affected by snow on Monday morning. Photo / NZTA

The wild winter weather created chaos across parts of Otago and Southland during the weekend, and forecasters are urging southerners to brace themselves for more of the same over the next few days.

Heavy rain, snow showers and winds gusting up to 100km/h kept emergency services busy in Dunedin with small landslips in Caversham; heavy flooding in Marne St, Andersons Bay; fencing and a fallen tree over roads; and ice on the Northern Motorway.

Wanaka residents woke up to a major dump of snow on Sunday morning. Photo / George Heard

A police spokeswoman said it was a similar scene in Central Otago and the Lakes area.

Heavy rainfall yesterday caused flooding on State Highway 6 between Luggate and Cromwell as well as at the intersection of Frankton and Perkins Rds, in Queenstown.

Police were also alerted to several weather-related incidents across the region as cars struggled in slippery conditions, including a car which slid backwards on ice down Weaver St, Queenstown, about 3pm yesterday.

It became stuck and needed to be towed. No injuries were reported, she said.

Ski fields made the most of the snow storm on Saturday, but after snow drifts reached about a metre and more heavy snow fell overnight, several closed their gates yesterday.

Glenorchy residents woke up to a major dumping of snow on Sunday morning. Photo / George Heard

MetService meteorologist Stephen Glassey said temperatures dropped below zero for much of the region, including Dunedin Airport where it dropped to -4.4degC yesterday morning.

He said snowfall was heaviest in the Lakes area and the Milford Rd where about 70cm fell at the Homer Tunnel; and in a rare event, it fell to sea level on Stewart Island.

- Additional reporting Otago Daily Times