Two people were killed in one accident on the A4 near Newbury, Berkshire, and a man died when his car burst into flames in a head-on collision on the A361 near Highworth in Wiltshire.
In Maidenhead, Berkshire, a woman escaped serious injury when a tree crashed on to her car. Fallen trees also blocked the A5, A6 and A600 in Bedfordshire.
Earlier in the day, the northbound M1 was blocked for several hours after two lorries collided, causing 12-mile traffic jams. Overturned lorries also blocked the M6 in Cheshire. The RAC said it had received thousands of calls - 'more than double the normal volume' - from stranded motorists.
Winds reaching 70mph lashed the capital during the early evening, uprooting trees and sending shop hoardings flying.
Shoppers narrowly escaped injury as they ran for cover when scaffolding on the Concorde shopping centre in Shepherds Bush, west London, came crashing down.
In Strathclyde, flooding and snow combined to make driving hazardous, while the A814 between Helensburgh and Gairloch was blocked by floodwater.
Police in the West Country were advising motorists to stay at home, and the Severn Bridge, linking Wales and England, was closed to high-sided lorries. The road bridge over the Cleddau Estuary in Dyfed, west Wales, was closed to all traffic.
Sealink and B & I Line sailings from Dublin to Holyhead in Anglesey were halted, and Sealink's service from Rosslare to Fishguard in South Wales was seriously disrupted. Flights from Shannon airport in the Republic of Ireland were also disrupted.
Many roads in the south-west of Ireland were blocked by flooding, and thousands of acres of farmland were under water.
The high winds are expected to continue to sweep across Britain before easing off later today.
Sport was also disrupted when Chelsea's FA Premiership clash with their London rivals, Wimbledon, was called off for safety reasons just over an hour before kick-off when gales struck the Stamford Bridge ground.