The MetService advise that a low and associated front will be approaching the country from the Tasman Sea on Monday.

'This weather system is forecast to move onto the South Island early Tuesday,” says a MetService spokesperson. 'Then the low moves away to the southeast late Tuesday, while the associated front moves northeast across the North Island through Wednesday."

A cooler south to southwest change is expected to spread north across the South Island behind the front late Tuesday then the North Island on Wednesday.

"Strong westerlies should affect much of the country on Thursday."

There is moderate confidence of warning amounts of rain in Fiordland, Westland and the headwaters of Otago and Canterbury lakes and rivers during Monday and Tuesday.

On Tuesday, there is also moderate confidence of warning amounts of rain about the ranges of Buller, Nelson, western and northern parts of Marlborough, the Tararua Range, northern Taranaki, Taumarunui and Taihape, as indicated on the chart.

There is low confidence of warning amounts of rain about the eastern ranges of Bay of Plenty on Tuesday.

'In addition, there is moderate confidence that north to northwest winds will reach severe gale in exposed parts of Fiordland, Southland and Otago except Dunedin and North Otago on Monday.

'There is also moderate confidence of northwesterlies rising to severe gale in exposed parts of Canterbury High Country, Marlborough, Wellington and Wairarapa during Monday and Tuesday.

'On Wednesday, there is low confidence of southwest winds reaching severe gale in exposed coastal parts of Westland and Buller, northwest Nelson and in the west of the North Island from Northland, Auckland, Coromandel Peninsula to Taranaki, as indicated on the chart.

'There is low confidence of southwest winds reaching severe gale in exposed parts of southern Fiordland, coastal Southland including Stewart Island, coastal areas of Clutha and Dunedin on Wednesday, then low confidence for severe westerly gales for the same area during Thursday. There is low confidence of west to northwest winds reaching severe gale in exposed parts of Wairarapa and Hawkes Bay south of Hastings during Thursday.”