Lightning strikes left thousands facing travel problems on one of the busiest days of the year tonight.
Sudden storms hit the great summer holiday getaway with rail passengers encountering delays and cancellations on busy commuter routes.
Services between London Paddington and Reading, Swindon, Bristol and South Wales were "severely disrupted" due to signalling problems in the Twyford area between Reading and Maidenhead caused by an earlier lightning strike.
Operator First Great Western said it was introducing a reduced timetable for customers travelling to and from Paddington.
Similar problems caused "major disruption" to all routes across the South West Trains network, with services between London Waterloo and Surrey and Exeter affected.
SW Trains said it was necessary to "significantly reduce" services after a lightning strike in the Surbiton area and signalling problems at Waterloo.
Commuters at Paddington and Waterloo posted pictures on Twitter showing the stations looking extremely congested.
Myles Dyer ?wrote: " I must admit, I hadn't planned spending Friday night in London Paddington station. All trains delayed or cancelled!"
Andy Burne tweeted: "A bsolutely chaos at Waterloo station, trains cancelled, station full of sweaty people."
SW Trains apologised for the problems. A statement on the firm's website said: " An incident at Waterloo resulted in a temporary failure of the signalling equipment, which initially affected Platforms 1 - 7 and then narrowed down to Platforms 1 - 4.
"This was rectified however we then experienced a lightning strike which resulted in the loss of all signalling between Surbiton & Woking.
"Once the lines re-opened, it was unfortunately necessary to significantly reduce the number of trains on our network.
"Our busy rail network into London Waterloo is dependent on using the lines through Woking & Surbiton and the closure of the line, coupled with trains, guards and drivers being out of position, has resulted in disruption for the majority of the day.
"We would like to thank our passengers for their patience and understanding today. We will continue to work through the night to ensure that trains and train crew are in the correct positions to enable us to operate our full timetable from the start of service on Saturday."
On one of the busiest travelling days of the year, there were other problems on the railways.
An electrical supply problem meant delays to trains between Pitsea and Shoeburyness in Essex, while a person being hit by a train led to delays to services between King's Cross station in London and Stevenage in Hertfordshire.
In East Anglia a broken-down train led to hold-ups between Felixstowe/Lowestoft and Ipswich.
There were also problems on the Tube tonight, with severe delays on the Victoria Line because of a signal failure at Walthamstow Central, east London.
The difficulties came after Network Rail warned of future disruption on the London to Scotland West Coast main line.
Due to vital work being carried out at Watford, the West Coast line will be closed between Saturday August 9 and Monday August 11, Saturday August 16 and Monday August 18 and Saturday August 23 and bank holiday Monday August 25.
Network Rail said the closures will affect passengers from across parts of Scotland, the West Midlands and the North West who plan to travel to London along the West Coast line. London Midland passengers will also be affected.
On the roads there were holds-ups on the M18 in East Yorkshire due to an accident involving two lorries. There were also jams on a number of other major routes including the M25, the M5, the M6 and the M11.
Meanwhile an easyJet plane carrying 154 passengers from Bristol to Barcelona had to divert to Reus airport in Spain after being hit by lightning on its descent.
The aircraft landed safely and the passengers were taken on to Barcelona.
Darren Williams, a student, posted the message: "Just flew through a monster storm, plane hit by lightning and we were diverted to Reus Airport.
"Worst flight I've ever been on...Currently sat on the plane waiting to see what's happening next."
An easyJet spokesman said: "The aircraft is equipped to safely withstand lightning and at no point was the safety of the flight, passengers or crew onboard compromised.
"Passengers disembarked as normal and will continue their onward journey to Barcelona by road. We apologise for any inconvenience experienced. A full inspection of the aircraft has been scheduled."
Today and tomorrow and the subsequent Saturdays in August are expected to the busiest days of the summer on the roads.
The first of an estimated two million Britons who are flying abroad over the weekend headed off today.
Spain is the number one destination for those hitting continental hotspots, according to travel organisation Abta.
Bookings to Greece and Turkey have also been going well, while for those travelling further afield Dubai, Mexico and Florida are among the most popular destinations.
The recent hot weather has also boosted the numbers taking last-minute trips in the UK, while short-haul favourites include Barcelona, Amsterdam, Rome and Paris.
In south-east England, around 450,000 passengers will be departing from Heathrow this weekend, 295,000 from Gatwick, 140,000 from Stansted and 79,000 from Luton.
More than 100,000 will be leaving from Scottish airports, with 50,000 from Glasgow alone, while 162,000 are due to depart from Manchester, 70,000 from Birmingham, 45,000 from Bristol and 37,000 from East Midlands airport.
Other regional airports, ports and the Channel Tunnel will also be extremely busy over the weekend with hundreds of thousands of people leaving the country.
A total of 67,000 holidaymakers will be heading off to Paris and the south of France on Channel Tunnel high-speed Eurostar trains over the weekend.
The Met Office had issued severe weather warnings for today for areas in the south and east, saying heavy showers or thunderstorms were expected to develop in the afternoon.