Snow is now expected to fall across the central North Island and storm-battered regions in the south tomorrow as the country freezes in a brutal cold snap.

A trough is due to hit the country later today bringing rain to most places and bitterly cold weather.

It's bad news for regions hit hard by recent storms. The south of the country is still mopping up from extensive flooding. More than 40 properties around Mangaweka are still without power nearly two weeks after a major snow storm wiped out poles and lines in the central North Island.

MetService warns snow is expected to fall to 400m in water-logged Canterbury and to 700m in the central high country of the North Island.

#Christchurch lowered to a chilly -2.5C this morn. It should heat up to 14C 2day, but a front 2morro means the forecast max is only 10C❄️^AC pic.twitter.com/vJ6UNaja7S

— MetService (@MetService) July 25, 2017

The first watch has been issued for heavy rain in southern Westland and a road snowfall warning is in force for the Milford Rd.

MetService says up to 5cm of snow may fall on the road today.

In a severe weather outlook MetService says snow is set to fall about Otago, Canterbury and Marlborough down to 400m tomorrow and Friday.

Road Snowfall Warning issued for Milford Rd https://t.co/QEAmxT6z1f

— Severe Weather Info (@MetServiceWARN) July 25, 2017

Rain is also expected for eastern districts of the South Island hard hit in last week's floods.

Heavy Rain Warning issued for WSTLD https://t.co/cfu90E0Wfg

— Severe Weather Info (@MetServiceWARN) July 25, 2017

A swathe of warnings and watches were likely to be issued today as MetService met with council officials in the south dealing with widespread flooding and slips from last week's storm.

On Friday the front crosses the North Island with gales likely to buffet the capital.

The weekend starts on a crisp cool note with bitterly cold air, clear skies and light winds in the south which eventually spreads north by Sunday before the next round of bad weather hits next week.