Cities along the Thames River in Surrey were at a high risk of flooding Britain's Environmental Agency said. The Thames has recorded some of its highest levels in 60 years.
The storm has been blamed for at least one death Friday, a 77-year-old man who was hit by a falling tree, the Daily Telegraph said.
Seventeen severe flood warnings have been issued and at least 16,000 homes were without power, the London Evening Standard said.
British Prime Minister David Cameron pledged to "fight on every front to help people" in a "massive national effort."
Winds brought down high-voltage power lines in Wales, sparking a huge fire on a peat bog, officials said. Weather officials posted a weather warning for high winds in the southeast.
Scientists said the red squirrel habitat in Durham county has been decimated because thousands of trees have been toppled by the winds. The red squirrel is a protected species.
Since Jan. 29, more than 181,000 homes have been protected and at least 200,000 homes have been sent a flood warning following the wettest January since 1766, the agency said.
Water levels have been monitored so flood warnings could be issued quickly, officials said. Sandbags and temporary barriers have been placed along riverbanks, but government officials warned residents in flood alert areas to be prepared for flooding.
Chris Bainger of the Environmental Agency said Alney Island could expect "some over-topping of [temporary barriers], which is linked to a tidal surge coming up the river and also the fluvial water coming down and coming together in this area."
Cameron visited Blackpool Friday on his latest leg in touring flood-hit areas, repeating his pledge that money was "no object" for relief efforts. He also acknowledged that the extreme weather would "have an effect" on Britain's economy.