A front preceded by a strong moist northwesterly flow is due to moves northeast across the country on Tuesday, says a MetService spokesperson.

"There is moderate confidence that warning amounts of rain will accumulate in the Westland District, about the headwaters of the Otago and Canterbury lakes and rivers, Tararua Range and Mt Taranaki.

"There is high confidence that the Canterbury high country will be affected by severe northwest gales and moderate confidence that Wellington will be affected by severe northwesterly gales."

On Wednesday, September 4, a showery west to southwest flow is forecast across New Zealand, with no severe weather expected.

By Thursday, westerlies and rain are likely to develop in Fiordland and the south of Westland but severe weather is considered unlikely.

A front is forecast to move slowly north over the south of the South Island on Friday, September 6, bringing rain, mainly in the west.

There is low confidence in warning amounts of rain for Fiordland and the Westland District," says a MetService spokesperson.