MetService has issued a severe weather warning for Westland, Buller, Nelson, Canterbury, Fiordland and Wellington.
A strong, moist north to northwesterly flow is bringing heavy rain to the west coast and is expected to move north today to reach the ranges of northwest Nelson this evening.
The largest accumulations are expected in the ranges from Westland to northwest Nelson, where a further 80 to 90mm of rain could fall with some spill over into the headwaters of the lakes and rivers of Canterbury.
MetService is warning that rivers and streams may rise rapidly.
Northwesterlies with severe gales gusts of 120 km/h are expected in exposed parts of Wellington until midnight tonight. Winds of this strength may cause damage to powerlines, insecure structures and make driving hazardous.