Severe gales and heavy rain are set to lash the central South Island and lower North Island overnight on Wednesday.
Wind gusts of up to 130km/h are expected to hit Otago and Canterbury, with similar strength gales in Wairarapa and central Hawke's Bay.
MetService says the winds could cause damage to powerlines in the area and is warning people to take care on roads.
Heavy rain has also begun falling in Fiordland and is expected to continue until early on Thursday.
Flash flooding is possible and rivers could rise rapidly in the area.