Heavy rain is expected for parts of the South Island, with severe gales possible in central New Zealand.
The heavy rains have already hit Fiordland, as active fronts move their way up the South Island.
The weather, which is due to reach the North Island tomorrow, is bringing lower temperatures, rain and potentially thunderstorms.
MetService forecaster Alwyn Bakker says Milford Sound had around 40mm millimetres of rain overnight.
He said the spell of fine weather has broken down, and a system of low pressure has arrived from the Tasman Sea.
A heavy rain warning is in place for the Westland ranges south of Otira. MetService said 80 to 100mm of rain is expected with possible thunderstorms.
The area may also see another heavy burst of rain in the morning, MetService said.
It said a low is expected to develop near the Otago coast this evening, bringing a period of southwesterly rain to Southland and eastern Otago, where rain amounts could approach warning criteria.
Strong wind watches are in force for the Canterbury High Country, Marlborough, Wellington, and Wairarapa including the Tararua District.