Severe flooding is causing holidaymakers to pack up and leave parts of Otago

Up to 100 millimetres of rain could pelt the region this evening, with plenty of roads hit by flooding.

The Maerewhenua river in the Waitaki town of Duntroon has burst its banks.

Resident Katrina Mclennan says locals had to step in to help holidaymakers evacuate from the town's flooded Domain camping area.

She says after a lifetime of living in the town, this is the highest she's ever seen the river.