Strong wind watches are being issued as howling gales strike the lower South Island and Hawke's Bay.
Blustery conditions will whip up some big waves and push more rain on to the wet West Coast.
"An active front, preceded by gale westerlies and followed by gale southwesterlies, is forecast to move north across southern and central New Zealand during tonight (Saturday), and then move away to the east on Sunday," MetService warns.
MetService says west to southwest gales could become severe in exposed coastal parts of Dunedin, Clutha, Southland and Stewart Island.
Westerly gales could also become severe in exposed parts of Hawke's Bay south of Hastings, and Wairarapa north of Masterton.
The colder air flow also means rain will fall as snow higher up in the Southern Alps.
"The angle of the wind flow means the bulk of the precipitation (both rain and snow) will be in the South Island with rain on the West Coast and snow in the Southern Alps," WeatherWatch says.
"In the North Island only showers are coming through and with stronger winds these showers won't linger long, hence the lower rainfall totals there.
"Dangerous waves are also impacting the country as we go through Sunday and Monday - not good days to be on the water with not only large waves in many places but also gale force winds in marine areas too until later on Monday."