It's set to be a wet and windy end to the year for most of the South Island and lower North.

Heavy rain and northerly gales are expected about parts of the South on Wednesday, with a period of heavy rain about Mount Taranaki.

Rain could reach near-warning levels in Otago and Canterbury headquarters tomorrow, for the early morning to late afternoon.

The bad weather is set to stick around into the evening for Buller, Nelson, Marlborough and Wellington.