Snow is falling to sea level in Dunedin, with heavy falls expected in the higher parts of Fiordland, Southland and Otago and on Banks Peninsula overnight and tomorrow.
Strong winds are also expected for parts of Stewart Island, Southland, Otago and Banks Peninsula.
Looks like the south is about to wake to a lot of snow in the morning -This was taken by my sister in Gore pic.twitter.com/1Xx2knOwq9— Mike Puru (@MikePuruNZ) May 24, 2015
Duty meteorologist Leigh Matheson said a very cold polar airstream was moving up the South Island and was close to Wellington.
She said the bad weather would continue tomorrow, with rain and strong winds in Fiordland, Southland Otago.
"Those showers will be also clipping Banks Peninsula who are also expected to get very strong south-westerlies and snow, but it misses Canterbury although the showers will persist around Auckland and Northland for much of the day."
Snow is also expected overnight on the Rimutaka Hill Road and the Desert Road, but is not expected to be heavy.
Snow showers affecting parts of Southland and Otago from tonight through to Monday afternoon, see warnings at http://t.co/os2FgIccAM ^HG— MetService (@MetService) May 24, 2015
Apart from the cold, this polar blast is also bringing some very large SW swells. Cook Strait forecast is here http://t.co/7A6X3F66dn ^SG— MetService (@MetService) May 24, 2015
Up to 20 centimetres of snow is expected to fall in the southern parts of Central Otago, and above 300 metres around the lower South.
About 15 centimetres of snow could fall on Dunedin's higher suburbs, and five to 10 centimetres is expected across the rest of the city.
Mount Hutt ski area manager James McKenzie, who is among those who will welcome the cold weather, said the field should get five or six centimetres of snow.
Mr McKenzie said his staff have been using snow machines but every little bit helps to get a solid foundation for the field's opening weekend on 12 June.
The strongest winds are likely in the east of the South Island.