A chilly polar blast is set to hit the country after an unusually warm week.

Cold southerlies could bring snow to low levels - 400-500m - in the South Island on Monday and Tuesday.

MetService forecaster John Law told Morning Report temperatures would return to normal winter levels.

LIsten: Temperatures to plunge as polar blast heads towards NZ

"We're not out of winter just yet, we may be lulled into a false sense of security with some of those high temperatures we'll see over the next couple of days."

Anyone planning to travel around the mountain passes in the South Island next week should watch the forecast, Law said.

By the middle of next week there may be some snow in the central North Island as well, he said.

"Definitely the time of the year to take extra care and extra time on the roads."