In Northern Ireland’s second city, Londonderry, a man was killed when the vehicle he was driving was blown off a bridge and plunged 100 ft (30 metres) onto a riverbank.
A second driver was killed in eastern Scotland when a lorry rolled onto his car. The storm, one of the strongest to hit northern Britain in a decade, was blamed for a third death in Dundee, Scotland, but details were not immediately available.
Scottish Hydro Electric said 60,000 people had lost power and repairs were delayed by the weather, which brought heavy rain and snow to some areas.
A Spanish fishing trawler carrying 19 crew went missing overnight in rough waters about 120 miles (190 km) off the coast of Scotland, but was later spotted by a Royal Air Force (RAF) surveillance aircraft.
"It appears all on board are safe," an RAF spokesman said. With possible widespread damage to trees, structural damage to buildings and coastal flooding at high tides, the Met office warned motorists and others to avoid unnecessary travel.
"Driving conditions will become extremely dangerous. High- sided vehicles could be easily overturned, especially if unladen," it said in a warning for northern Scotland.
The severe weather followed a storm that killed three people, caused rivers to overflow and widespread damage to parts of northern Britain at the weekend.