MetService advises that a frontal rain band preceded by a strong north to northwest flow will be approaching the South Island from the Tasman Sea on Tuesday.

The front should move north over the South Island during Wednesday and over the North Island on Thursday,followed by a disturbed west to northwest flow.

"Late Tuesday and into Wednesday, there is moderate confidence of significant heavy rain in Fiordland," says a MetService spokesperson.

"For Wednesday and Thursday, there is mostly moderate confidence that rainfall amounts will reach warning criteria about western Tasman, Buller and the Southern Alps, with significant spillover into the headwaters of the Canterbury and Otago lakes and rivers; however for Westland confidence is high."

MetService says also on Thursday, there is low confidence of a period of significant rain for the Bryant and Richmond ranges and also for the ranges of eastern Bay of Plenty.

"On Friday, there is low confidence that rainfall amounts will reaching warning criteria in Westland.

"In terms of wind, on Tuesday and Wednesday there is high confidence of severe north to northwest gales about exposed parts of the Canterbury High Country, Queenstown Lakes, Fiordland, western Southland and Stewart Island, while there is low confidence for the remainder of Canterbury, Otago, Southland, and also in Westland," says a MetService spokesperson.

"Additionally, there is also moderate confidence for severe north to northwest gales about exposed parts of Wellington including the Remutaka Hill Road on Wednesday and Thursday, and a low risk of severe northwest gales in exposed places of Marlborough and Wairarapa."