Parts of the South Island are in for a drenching on Monday.
A severe weather watch is in place for Westland, Buller, Nelson and Canterbury.
A front over the Tasman Sea is expected to move across the South Island on Monday, preceded by moist northerlies.
A period of heavy rain is forecast for the West Coast and Alps during this time.
The heaviest falls are likely to be in the ranges of Westland, Buller and western Nelson, where rainfall amounts may reach warning criteria.
A period of rain is expected in Canterbury on Monday as strong and unseasonably cold southerlies follow the front.
Heavy rain is also predicted in the Canterbury High Country on Monday, where amounts may approach warning criteria.
MetService is warning people to keep up to date with the latest forecasts.
Find the latest weather update for your region here.