Snow has closed or restricted access to several alpine passes in the South Island.

Photo: RNZ / Alexander Robertson

Metservice has issued a heavy snow warning for Fiordland and southern Westland, forecasting up to 30cm of snow falling as low as 500m in Westland, while up to 40cm could be dumped on parts of Fiordland.

The heaviest falls are expected this morning.

Snow settling in Queenstown! Snow expected 200m southwest South Island, and 600m possible for Central North Island. Share your here ^TA pic.twitter.com/y71VovafMk — MetService (@MetService) September 8, 2017

The snow has already closed the Lewis and Lindis Passes, and a section of the Milford Road between Chasm Stream Bridge and the Hollyford Valley Rd intersection.

The Transport Agency said chains were essential for the rest of the Milford Road, along with Arthurs Pass.

Metservice said as well as disrupting travel, the snow could damage trees and powerlines, and the cold conditions may cause stress for livestock.

It also had a strong wind watch in place for Canterbury, especially the high country and Banks Peninsula, saying northwesterlies could become severe gales in exposed places.

Snow warnings are in place for the remaining alpine passes, as well as the Desert Road and the Crown Range.