A front is moving through on Sunday and may bring significant amounts of precipitation in some isolated areas, including snow and freezing rain along the South Island mountains.
Since northerlies are brought by the incoming lower air pressure and departing high, temperatures across the country will be milder than lately (and milder than average) on Sunday.
The whole country will have some amounts of rain as the area of lower pressure is crossing over NZ for the next day or so.
As a side note, 5 metre high waves are expected from Monday night to Tuesday morning.
Dry weather with southerlies and normal winter temperatures return on Tuesday.