Devon County Highways said it had received about 300 calls about storm disruption since Saturday evening.
Steve Marks, area duty manager for Devon, Cornwall and the Isles of Scilly at the Environment Agency, said: “It’s really our rivers in Devon and also east Cornwall which have had the most rain and the bigger rivers are continuing to rise.
“We’re expecting more rainfall throughout the day so it really is an important message to please stay up to date with what the rivers are doing through our flood warning service., external
“And of course, be safe, be prepared and be ready to act if those rivers do potentially cause flooding.”