Weather: Chaos continues across the South Island as heavy rain bites

The clean-up of the chaos on the South Island's West Coast has begun after heavy rain drenched the region.

Westland District Mayor Bruce Smith told The AM Show the West Coast has managed to handle most of the immense flooding.

"The rivers have already started coming down, and look the Hokitika Gorge burst monitors showed the second highest reading in 50 years," he said.

"The photos, amazing, just absolutely amazing, frightening."

The Goat Creek bridge on State Highway 73 south of Otira, has been washed out.

Parts of State Highway 6 and State Highway 73 are closed due to slips and surface flooding. The NZTA is also warning motorists of surface water along State Highway 6 from Fox Glacier to Haast.

Westland High School in Hokitika has been closed as buses are unable to navigate roads.

Twenty-five students from Otago Boys' High School are stuck at the school's lodge in the Mount Aspiring National Park.

A creek became too dangerous to cross but the school says there is plenty of food.

Heavy rain warnings remain in place on Friday for the west coast of the South Island and MetService expects the lower North Island will continue to be buffeted by gales across the morning.