The MetService has issued a severe weather warning as a disturbed flow brings heavy rain to some parts of the country.
The west to northwest flow will bring outbreaks of heavy rain to the west of the South Island, including the Southern Alps, and also to western parts of the lower North Island.
A strong, cold southerly change is expected late tomorrow and early Tuesday as a deep low moves east across southern New Zealand.
Periods of heavy rain are expected about Fiordland and Westland today and tomorrow.
Further north, periods of heavy rain are forecast for the Buller and Tararua Ranges.