Three motorists were killed as storms with winds up to 124mph hit Scotland, Northern Ireland and northern England.
A driver died after his lorry was blown off a Londonderry bridge
Some 60,000 people were left without electricity in Scotland after winds downed trees and telegraph poles.
Two lorries were blown over in Scotland and Northern Ireland, killing one driver and another motorist. A separate Scotland crash killed a third motorist.
The BBC Weather Centre said the storms would peak around dawn on Wednesday in some areas.
With possible widespread damage to trees and buildings and coastal flooding at high tides, the Met Office has warned against unnecessary travel.
A driver was killed when his car was crushed by a lorry blown over on the A1 near Burnmouth, in the east of Scotland. The lorry driver suffered minor injuries.
In Tayside, a van driver was killed when his vehicle and a lorry were involved in a collision on the A90 northbound.
A lorry driver died after his vehicle was blown off Foyle Bridge in Londonderry, as 90mph winds battered Northern Ireland.
The strongest winds were measured at 124mph on North Rona, in the Western Isles.
Winds of at least 70mph have hit most of Scotland, along with rain, sleet, thunder and lightning.
Coastguards said they had lost contact with a Spanish fishing boat that issued an emergency alert 120 miles out in the Atlantic.
Fort William Coastguard evacuated five elderly residents from 4ft flood waters in their housing complex in Oban, while Oban Coastguard rescued a man floating away inside a camper van.
Scottish Hydro Electric said 60,000 people had lost electricity in Argyll, the Western Isles and Highlands, and also in the central belt.
A spokesman added: "We have had to stand our repair staff down for the night because it's simply too dangerous for them to work in these high winds."
Scottish Water said lack of electricity might affect some water supplies.
Across Scotland, roads are blocked, most of the main bridges are closed, ferry services have been abandoned and rail routes suspended.
The Diabaig and Scalpay areas in the Highlands were without 999 services early on Wednesday, while the Scottish Ambulance Service said Highland residents should only call for assistance in life-threatening situations.
The Scottish Environment Protection Agency has issued 13 flood warnings, as well as 21 flood watches.
Emergency services were braced for flooding in Stornoway on the Isle of Lewis, on Skye and on Lochalsh in the Highlands.
Northern Constabulary said a number of houses had been flooded by coastal waters at Lochyside and Caol, near Fort William.
Mallaig Police Station in the Highlands was flooded following a high tidal surge at around 6.45pm on Tuesday.
The severe weather was expected to move southwards to north-west England overnight.
By Tuesday evening, 15 Environment Agency flood warnings were in place in England and five in Wales. There were also an additional 56 flood watches.
Warnings of high winds prompted Sellafield nuclear plant in Cumbria to send home hundreds of office staff until Thursday.
Buildings at the plant suffered external damage from winds at the weekend.
Warning system review
The weather has hampered salvage efforts in Carlisle, from where thousands of homes were evacuated due to flooding at the weekend.
Up to 10,000 homes in Hexham, Northumberland, have been without running water since the weekend storms. Repairs were due to start on Wednesday morning.
Three people were killed and two went missing after torrential rain and gales swept north England and elsewhere.
Carlisle United's Brunton Park pitch was hit by heavy flooding
Environment Minister Elliot Morley has announced a review of the flood warning system, saying early indications showed many people had not been alerted to the flood danger at the weekend - despite the activation of the system.
Proposals are being developed for a new Environment Agency flood defence scheme to provide added protection, he told the House of Commons.
Mr Morley also told MPs that local authorities could claim financial help for the clear-up.
Call the Environment Agency's Floodline for flood warnings on 0845 988 1188.