Strong wind watches are in place for the Canterbury High Country, Marlborough, Wellington and Wairarapa.
While much of the country has experienced relatively high temperatures in the past few days, the southerly change will spread up the South Island on Tuesday and over the North Island on Wednesday.
"The difference will be most notable in the South Island, with a few locations set to see around a 10C drop in temperature." MetService meteorologist Alwyn Bakker said.
Temperatures in Christchurch are expected to drop from an afternoon high of 22C on Tuesday to 7C on Wednesday morning.
Wellington is expected to reach a high of 17C on Tuesday but temperatures will plunge to 10C on Wednesday morning.
A high of 22C is forecast in Auckland on Tuesday but that is set to drop to 17C on Thursday.
The change is predicted to bring snow down to 600 metres in Southland, Dunedin and the Southern Lakes area from tomorrow afternoon, and to 700 meters overnight in the Canterbury High Country.
MetService is calling it "the first significant snowfall for the year".
Road snowfall warnings are in place for Arthur's Pass (SH73), Porters Pass (SH73), Lindis Pass (SH8), Crown Range Road and Milford Road (SH94).
- Additional reporting Otago Daily Times