British Prime Minister David Cameron promised the government would "ensure everything is being done to help" after winds and torrential rain left one person dead and forced hundreds from their homes.
His comments came as the UK's Environment Agency revealed more than 800 homes have been flooded.
A 21-year-old woman was killed and two people were seriously injured in Exeter, Devon when they were crushed by a tree.
It follows the death of a man on Thursday, who died when his car became wedged under a bridge near a ford in Chew Stoke, Somerset.
A 50-year-old man also died after falling into a canal in Watford on Saturday.
The agency issued more than 550 alerts, including 280 flood warnings - the second strongest alert.
People were forced to flee their homes last night as flood water and torrential rain caused "serious threats to life" in villages in Cornwall.
Special rest centres were set up in the worst-hit villages, though Cornwall Council said these were all later stood down as people returned home or went elsewhere as flood threats stabilised.
Severe flood warnings have been issued for Lostwithiel, Helston, Polperro and Perranporth in Cornwall, where rivers threatening to burst their banks.
Roads have also been closed across the region as highways became impassable because of rain and debris.