Alexandra will get the worst of the winter chill overnight with temperatures set to drop below -2C.
The MetService has updated its forecast predicting snow to fall near to sea level in Dunedin today.
Bitterly cold gales of 120km/h are also expected to lash the south.
This afternoon's satellite images show the next front moving into Southland and showers feeding into the west. Images courtesy of JMA ^JL pic.twitter.com/Frq93TDLoc
There was a light dusting of snow in the township of Naseby overnight.
The MetService says heavy snow is expected to coat parts of the Southern Lakes and Central Otago from the Crown Range southwards, Dunedin, Southland and Clutha.
Fierce gales are battering eastern regions and monster 6m swells will pound the country's western coastline today. The MetService said the biggest waves could easily double to 12m in height - and be incredibly powerful.
Colossal 9m waves are due to hit Puysegur Pt in the far southwest of the South Island this afternoon.
People are being warned to be careful on coastal roads at high tides.
Large southwest swells through the weekend on both coasts, watch coastal roads at high tides. ^TA pic.twitter.com/skRiPyNg6I
Firefighters say they were busy overnight securing roofs and clearing trees and powerlines felled by the destructive gales from Canterbury to Wairarapa.
A Fire Service spokesman said it had about half a dozen callouts across the Canterbury region between 7.30pm and 1am as the winds picked up.
In the North Island trees and powerlines came down across roads east of Woodville.
But the worst weather is reserved for the next 24 hours, and snowfall warnings have been issued for all South Island alpine passes and the Dunedin to Waitati highway.
Snow is expected to coat Queenstown today as temperatures dive from 10C to below zero.
The NZ Transport Agency said the highway linking Te Anau to Milford Sound was likely to be closed overnight and up to 15cm of snow is expected today.
Queenstown Lakes District Council said the Crown Range had a light dusting of snow overnight.
The road was open but motorists were asked to carry chains or take an alternative highway.