MetService is warning of deteriorating weather conditions, with snow down to low levels in Otago, Southland and parts of the west coast of the South Island by Tuesday.
The agency says snowfalls of about five centimetres deep are expected down to 300 metres on Monday night and to sea level the next morning.
Severe gales buffeted Southland and Clutha on Monday night. In Southland, where wind gusts of up to 120km/h have been forecast, boat owners were advised to check that moorings are secure.
Federated Farmers said farmers should ensure that livestock have sufficient shelter, as it would be too late by the morning to save newborn lambs left out in the open.
Meanwhile, stormy conditions are forecast for Buller, Westland and Fiordland, with snow to 200 metres in the south overnight on Monday.