Torrential rain has closed part of a major highway on the West Coast

State Highway 6, from Ross to Franz Josef has been closed after extreme weather caused a wash-out.

Motorists have been advised to avoid the area, with the road expected to remain closed until at least 8am, when an assessment will be made.

MetService recorded more than 300 millimetres of rain in the southern part of Westland over the weekend - with some parts getting nearly 400 millimetres.

There were reports of flooded creeks and rivers encroaching on local roads.