MetService is forecasting rain ahead this week.

On Tuesday, January 30, a low should lie northeast of the North Island and be moving very slowly southwards, says a MetService spokesperson.

Meanwhile, a ridge of high pressure lies over the South Island.

There is low confidence that rainfall will reach warning levels about Gisborne/Tairawhiti and Hawke's Bay north of Napier.

The low should weaken and continue moving south during Wednesday to lie near the Chatham Islands at night.

The ridge of high pressure is expected to move over central New Zealand during the day.

There is low confidence that a rainfall warning will be required for southern Gisborne/Tairawhiti and the Wairoa District of Hawke's Bay on Wednesday.

There may also be heavy rain about the Chatham Islands, but it is unlikely to be enough to need a warning.

The ridge of high pressure should weaken during Thursday as a large trough approaches the country from the west.

MetSerivce says there is a minimal risk of severe weather on Thursday.

During Friday, the large trough is expected to move over the country, bringing strong winds and rain to many places.

For the west of the South Island, there is low confidence that heavy rain will require a warning. It is likely that the confidence will rise for some places over the coming days.

There is also low confidence that west to northwest winds about inland Canterbury, much of Marlborough, Wellington and Wairarapa, including the Tararua District, will get strong enough to need a warning.

At the Chatham Islands on Friday, there is low confidence that north to northwest winds will reach severe gale.