A burst of cold air from the Southern Ocean will sweep over New Zealand on Sunday and Monday, bringing a big cold change and a big temperature drop to parts of the South Island.
The same strong front that brought thunderstorms and powerful winds on Saturday will also see a "spring swing", with daytime temperatures dropping as much as 5 to 10C.
"Single-digit daytime highs are expected today in parts of Southland and Otago and tonight - heavy frosts with lows down to -3 or below for Southland, parts of Otago and frosts possible across the Canterbury plains overnight tonight," WeatherWatch warns.
"Below-normal temperatures will impact many parts of the South Island today and most of New Zealand tonight."
In parts of the upper and eastern North Island however it will be warmer than usual, due to the mild spring winds ahead of the cold front.
Rain will also develop across the eastern North Island where it will be welcomed by farmers and gardeners.
MetService says snow is possible down to 500m above sea level in the Canterbury region today and has road snowfall warnings in place for some South Island alpine passes.
Full details on the road snowfall warnings can be found here.
