The wintry blast that brought snow to high country areas of the South Island overnight is set to sweep up the country with gales and heavy rain.

Snow fell in high country areas of Otago and Southland overnight, closing roads.

MetService says snow fell down to 200m in Southland.

State Highway 94 between Te Anau and Milford is closed from Hollyford Road because of snow and a rising avalance risk, and is likely to remain closed until midday.

The Blackmount-Redcliff Road in western Southland has reopened after being closed for a time due to heavy snow. Photo: Southland District Council

MetService forecaster Heath Gullery said the cold weather system wasn't over yet.

Heavy rain warnings and watches are in place for north west Nelson, the ranges of Buller and the Richmond Range.

Mr Gullery said Up to 100mm of rain could fall in north-west Nelson.

Gales of more than 90 km/h are also expected for the Kaikoura coast and in Wellington.

Yesterday, temperatures dropped rapidly as the front moved up the South Island.

Main Image: A truck on the Blackmount-Redcliff Rd in western Southland. Photo: Southland District Council