Christchurch could see its first October snowfall in more than 50 years.
MetService is forecasting snow down to sea level across the South Island this week, with a polar blast expected to hit the country.
Temperatures are forecast to drop on Wednesday with Christchurch in for chilly lows of -1C.
MetService meteorologist Heath Gullery says the last time Christchurch saw an October snowfall was in 1969.