Meanwhile in the South Island a cold front will start to move through, bringing rain up the west coast towards the North Island.
A heavy rain watch is in place for Fiordland, Westland and Buller, as well as the Tararua Range.
It's not getting any better on Tuesday either - periods of rain and showers are expected for much of the country, though fine weather may show its face in parts of the South Island, aside from Southland and the West Coast.