This weekend is fairly mild in many areas and despite some coastal rain and showers in northern and eastern parts of the North Island, to begin with, Sunday is mostly dry.
The South Island has a cold front arriving in Southland around noon or into the afternoon.
By Monday the South Island is under the cold front and it will be moving into the North Island. By Tuesday all of NZ is colder with heavy snow around parts of the South Island. The system fades away by Friday.