MetService has issued a Severe Weather Outlook..

"Moist northwesterlies will bring heavy rain to the north and west of the South Island on Tuesday and gales to central New Zealand, while colder southerlies in the east bring snow to parts of Canterbury and Otago,' says a MetService spokesperson.

"On Wednesday a low to the west of the North Island is expected to direct a moist northeasterly onto the Island."

On Tuesday, there is moderate confidence of rainfall accumulations meeting warning criteria in Westland, and high confidence in Buller and western Nelson.

There is also moderate confidence for the remainder of Nelson and the far west of Marlborough. 

In the east of the South Island, there is low confidence of heavy snowfall over parts of Canterbury and Otago.

There is also moderate confidence in severe northwest gales from northern Canterbury over Marlborough to Wellington, Wairarapa and the Tararua District.

On Wednesday there is low confidence of warning amounts of rain for Northland, Auckland and Coromandel.