Weather: 'Wintry system' to bring heavy rain, strong winds and snow this week

Settled weather will move away from New Zealand this week, bringing rain, strong winds and snow with it.

A "wintry system" is passing over the country during the first half of the week - although forecasters don't think it will be as severe as last week's polar blast.

MetService says there will be heavy rain in the west of the country, strong northwesterly winds over the Southern Alps, and possible snow down to 100m in the far south.

"A front moves slowly northwards over the South Island on Tuesday, then moves more quickly over the remainder of the country on Wednesday, followed by a cooler southwesterly flow," the forecaster's severe weather outlook says.

"There remains uncertainty as to the snow level and how much snow will fall at this stage, but there is low confidence that a heavy snow warning will be required above 400 metres for parts of southern Fiordland, Southland, Clutha and southern central Otago."

WeatherWatch says Dunedin's hill suburbs could see some snow flurries on Friday.

"Windchill will again be below zero and with some parts of the South Island already in early lambing, farmers should be prepared," the forecaster said in a statement.

"Once again, cold air is the main feature and not heavy snow.

"Snow flurries are possible in Gore, Lumsden, Balfour, Te Anau, Queenstown, around Alexandra, Arrowtown, Twizel, Tekapo and further north into Waiouru in the central North Island and Desert Rd."

Heavy rain warnings are in place for Fiordland and the Westland ranges - starting from late Monday night until about 11am on Tuesday. Strong wind warnings have also been issued for the Canterbury High Country and Wellington and Wairarapa. 

The worst winds are expected in the High Country between 11pm on Monday and 11am on Tuesday, while severe gusts are expected to batter Wellington and Wairarapa between Tuesday from 2pm and 2am Wednesday.

"Strong wind gusts could damage trees, powerlines and unsecured structures," MetService says. "Driving may be hazardous, especially for high-sided vehicles and motorcycles."