The whole of Cornwall is set to be hit by 21 hours of scattered heavy showers as the Met Office issues an orange weather warning for the Duchy.
Both Cornwall and Devon have been put on flood alert by the chief forecaster at the national weather service, with "periods of heavy rain expcted to affect Cornwall during Wednesday evening and at times well into Thursday."
The amber weather warning, which aims to advise members of the public to "take extra care" and "be prepared," is valid from 6pm on Wednesday until Thursday at 3pm.
The warning from the Met Office reads: "An area of low pressure is likely to move north across the UK during Wednesday night and Thursday, bringing periods of heavy rain.
"The exact track of the low is still open to some doubt, but with saturated ground and following the rain of Wednesday morning, a further 20-40mm of rain is likely to run off leading to an increased risk of flooding across Cornwall and Devon.
"This warning will be kept under close review and the public are advised to monitor for updates."
Although dry weather is expected on Friday, there are indications that more heavy rain and strong winds could hit Cornwall over the weekend, particular on Saturday.
Cornwall Council has issued a statement to say that its officers from Highways, Environment, Fire and Rescue and Emergency Management services are monitoring the situation closely and are on standby to deal with any problems.
They have also urged residents in flood-prone areas to buy sandbags from builders merchants, DIY and hardware stores as "neither the council nor the Environment Agency has a statutory duty to provide sandbags," a spokewoman said.