More than 40,000 homes were left without power and commuters faced severe travel disruption after the worst storm in years lashed the UK.
Winds of almost 100mph have left houses across large parts of the South and East without electricity.
More than 40 railway lines have been cleared of fallen trees, with many more expected throughout the morning, Network Rail said.
The storm the South West shortly before midnight and moved north and eastwards throughout the early hours, leaving a trail of destruction.
Police said at least 125 trees were down across roads in Sussex by 6.30am, and Kent Police said at least 70 trees had been blown down across the county.
Scottish and Southern Energy (SSE) said more than 38,000 customers were left without power in Cornwall, Devon and Somerset, while Western Power reported a further 3,800 power cuts in the same areas.
Trains across the country have been disrupted, with many operators not expecting to run services until at least 9am.
Transport for London (TfL) said there was disruption to six Underground lines due to debris from the storm on the tracks.
The Bakerloo, Central, Jubilee, Metropolitan, Northern and Piccadilly lines were all partially closed while workers removed fallen trees and other obstructions, a TfL spokesman said.
The Environment Agency has 141 flood alerts in place across England and Wales, warning people to be prepared, and 17 flood warnings, with 15 in the South West.
Winds of up to 80mph have been reported, while a gust of 99mph was recorded by the Met Office at the Isle of Wight at 5am.
Major roads around the country have been closed, including both Severn crossings and the A249 Sheppey Crossing in Kent.
In central London, Whitehall was closed both ways between Parliament Square and Horse Guards Avenue due to a collapsed crane.
London Mayor Boris Johnson will chair an emergency resilience meeting involving all emergency services and relevant agencies later this morning.
“Clearly this has been a difficult night for many Londoners, and continues to be an incredibly trying morning,” he said.
“Transport for London, the boroughs and the emergency services are working flat out in an effort to keep London moving and minimise disruption as far as is possible.
“I want to thank all the agencies for their professional response in incredibly testing conditions, and I’d urge Londoners to check before travelling by going to tfl.gov.uk for the latest information.”
Numerous roads were blocked by fallen trees and other obstructions. These included the A12 in London, the A2 in Kent, the A21 in East Sussex, the A35 at Axminster in Devon, the A37 in Somerset, the A111 at Cockfosters in north London, the A112 in Walthamstow, east London, the A131 in Halstead and the A240 in Surrey where three trees are down.
Other tree falls affected the A338 at Hungerford in Berkshire, the A404 in Berkshire and the A3020 at Newport, Isle of Wight.
Flooding also hit motorists, with roads affected including the A427 in Northamptonshire and the A466 in Monmouthshire, South Wales.
In Greater Manchester, there were hazardous driving conditions on the M61 southbound between junction 5, at the A58 (Westhoughton), and junction 1, at the M60 (Swinton Interchange), because of surface water.
There was also reduced visibility due to surface water on the M62 in West Yorkshire.
East Midlands Trains said it would not run any trains in or out of London St Pancras International station until further notice. Stansted Express said it would have no trains running before 12 noon. Chiltern said it hoped to run its first train through Birmingham just after 10am.
At around 10am London Overground was able to get services running, albeit with severe delays, between Highbury & Islington (H & I) in north London and New Cross in south London and between H&I and New Cross Gate.
Virgin Trains’ services between London and Milton Keynes in Buckinghamshire remained suspended due to a blocked line.
Speed restrictions that had been hampering services run by Channel Tunnel high-speed train company Eurostar were lifted at around 10am, with services getting back to normal.