Rain and showers are being forecast for many parts of New Zealand this weekend.

From Friday onwards, the MetService is predicting a strengthening and unsettled west to southwest flow brings an extended period of rain and showers to many parts of New Zealand, mainly in the north, south and west.

The weather organisation's severe weather outlook says several features are embedded within this flow, and there is uncertainty about the location and timing of these features.

A shower or two is being forecast for the Bay of Plenty today, with rain expected to increase overnight.

Things are then looking fine for the next few days before more rain is predicted to move in on Monday.

"On Saturday there is low confidence for warning amounts of rain in Buller, Westland, and Fiordland; while about the hills and ranges of the central North Island from Waikato to Taihape and down to the Tararua Range, there is low confidence for warning amounts of rain from Saturday to Monday.

"Additionally, there is low confidence that westerly winds will rise to severe gale from Saturday to Monday in many North Island areas, and also about Nelson and the Marlborough Sounds. However, from Central Hawke's Bay to Wairarapa, there is moderate confidence westerly winds will rise to severe gale.

"Also, from Saturday snow is likely to affect higher roads and passes of Fiordland, Southland, Otago and along the Main Divide.

"On Sunday snow may fall to low levels in the south of the South Island and there is low confidence for warning amounts of snow above 400 metres in Fiordland, inland Southland, Clutha, and parts of inland Otago.

"For the South Island there is also low confidence that westerly gales could be severe about coastal areas of Fiordland, Southland and Clutha from Saturday to Monday; and for coastal parts of Dunedin, North Otago and Canterbury on Sunday and Monday."