MetService advise that a high is expected to cover much of the country over Sunday, while a weak cold front moves slowly north over the upper North Island.

The high moves slowly east on Monday, allowing a northerly flow to spread over the country ahead of a front approaching from the Tasman Sea.

This front is forecast to move east over the South Island and become slow moving about central New Zealand Tuesday night, before moving onto the North Island on Thursday while a ridge of high pressure builds over the lower South Island.

On Monday, Tuesday and Wednesday, there is a moderate confidence that rainfall accumulations will meet warning criteria about Fiordland and Westland, with a low risk about Buller and northwest Nelson on Monday, then moderate on Tuesday and Wednesday.

In addition, with the strong northerly flow ahead of the front on Monday, there is a low confidence that northerlies could approach severe gale about exposed parts of Fiordland, Southland, Otago and Canterbury.

Image: MetService