Authorities in the Upper South Island are hopeful the worst of intense rainfall has passed

A local State of Emergency's been declared for Nelson and Tasman, while Marlborough's remains in place.

Peak rates of up to 20 millimetres an hour are expected for the wider area until midday.

Nelson Mayor Nick Smith says heavy rainfall in the early morning has resulted in extensive flooding.

He says the greatest damage is in the lower stretches of the Motueka River, and other parts of Tasman - while there's been one area evacuated in Nelson.