Southern and eastern areas of the North Island could also get some frost over the weekend.
On Friday, MetService says most of the North Island will get showers which will clear by the evening.
Those in the south and east of the South Island will also get showers but these will clear by the morning, except for northern Buller and Kahurangi National Park.
On Saturday, Gisborne, northern Hawke's Bay, Buller and Kahurangi National Park may get some isolated showers throughout the day.
Over the weekend, Auckland can expect highs of around 18C while the forecast in Wellington on Friday is a high of 12C but 16C on Sunday.
In the South Island, Christchurch could reach 22C on Sunday - a 10C increase compared to Friday's forecast high of 12C.