MetService says a front will move up the country on Saturday.
A wet and windy Saturday is forecast for some with more settled but cooler weather expected on Sunday.
Meteorologist John Law said there would be unsettled weather this weekend as a front moved up the country on Saturday bringing some heavy rainfall towards the western facing coast and stronger winds.
"By the end of the day that wet weather and those stronger winds transfers towards the North Island as well."
The MetService says showers turning to rain are forecast for the north and west of the North Island on Saturday, but they will ease to isolated showers on Sunday morning.
In the South Island there will be rain in the south and the west which may be heavy on Saturday, but it is expected to clear in southern Westland, Otago and Canterbury later in the day.
More showers are expected in the south and west of the South Island on Sunday, but it is expected to be mainly fine elsewhere.
Beginning early Saturday, vigourous westerly to northwesterly winds are forecast to sweep over the South Island and lower North Island, with several strong wind watches and heavy rain watches in place. The winds are expected to ease on Sunday.
Law said the front was expected to move through fairly quickly and it was expected to clear by Sunday with more settled weather but cooler temperatures.
There would still likely be showers in the southern part of the South Island on Sunday, he said.