A northerly flow should cover New Zealand on Thursday, with bands of rain or showers affecting northern and western parts of the country.

A Heavy Rain Watch has been issued for Tasman District northwest of Motueka from Wednesday afternoon to early Thursday morning, and there is moderate confidence that the Watch will be upgraded to a Warning.

There is also low confidence that rainfall amounts about southern Westland and northern Fiordland will require a Heavy Rain Warning.

A front in the Tasman Sea spreads onto New Zealand during Friday, bringing a period of heavy rain to northern and western parts of both the North and South Islands. A strong northerly flow precedes the front.

Over the North Island, there is moderate confidence that rainfall amounts will reach warning criteria about central areas from Coromandel Peninsula, southern Waikato, Bay of Plenty and northern Gisborne/Tairawhiti to Taranaki, northern Whanganui and the central high country (including Tongariro National Park), and low confidence about Northland, Auckland, Great Barrier Island and northern Waikato,

In the South Island, there is moderate confidence that northerly rainfall will also reach warning criteria about Marlborough and Tasman/Nelson, and low confidence for southern Westland.

Additionally, there is low confidence that north or northeasterly winds could reach severe gale about exposed parts of the central North Island, the Kaikoura Coast and Banks Peninsula for a time late in the day.

The front should move off the country on Saturday morning, and a northwesterly flow spreads over the country.

There is moderate confidence that heavy rain about eastern Bay of Plenty and northern Gisborne/Tairawhiti will continue into Saturday morning, and low confidence that periods of rain about the Tararua Range will require a Heavy Rain Warning.

A west to northwest flow covers New Zealand on Sunday, with bands of rain or showers affecting western areas.

There is low confidence that periods of rain about the Tararua Range will require a Heavy Rain Warning.