The week ahead is mainly fine for the Bay of Plenty with some westerlies.

MetService is forecasting a weak front which will affect central New Zealand on Tuesday, while a southwest flow over the South Island will turn northwest.

On Wednesday, November 27, a moist northwest flow is expected to strengthen over the lower South Island ahead of a front approaching from the Southern Ocean.

"Later in the day, there is low confidence that rainfall accumulations could reach warning criteria in Fiordland, and also low confidence that northwest gales could become severe over southern parts of Fiordland, and areas of Southland near the coast, including Stewart Island," a MetService spokesperson said.

On Thursday,  the front is forecast to move onto the South Island.

"There is low confidence for warning amounts of rain in Fiordland, and in southern and central Westland, especially in the ranges.

"There is also low confidence that northwest gales could be severe over parts of southern Fiordland, Southland including Stewart Island, Clutha, Central Otago and Dunedin."

The front affecting the South Island is expected to become slow moving on Friday and should begin to weaken.