Britons setting off on a bank holiday getaway face travel chaos today as trains are disrupted by striking rail workers and engineering works.
Members of the Rail, Maritime and Transport union at First Great Western (FGW) are walking out for three days in a row over new trains.
The action will disrupt FGW services, which run from London to South Wales and the South West, with some cancellations already announced.
Improvement work is also taking place on the West Coast Main Line which will affect services from a number of key locations, including Birmingham, Manchester, Liverpool and Glasgow.
Many passengers will be forced to make multiple changes, use replacement buses and suffer extended journey times.
Planned works by Southern means trains will be disrupted from the south coast and Surrey in to London from Saturday to Monday.
More than 13 million drivers are expected to hit the road for trips over the long weekend, according to the AA.
A poll of more than 12,000 AA members found that 39% are likely to be on the road either for a day trip or overnight stay during the weekend, and the average trip will be around 90 miles.
This equates to the equivalent of more than 13 million drivers on leisure journeys, the AA said.
Weather forecasters have predicted cool and wet conditions over the bank holiday, with severe weather warnings issued for south-east England where thunderstorms are expected on Sunday.
There is a risk of torrential rain, lightning and localised flooding, the Met Office added.
MeteoGroup said Saturday and Sunday will see sunny spells and showers across much of the country, with most places experiencing maximum temperatures of just 16-19C (61-66F) although parts of the South East could reach the low 20s Celsius.
Monday is looking a better day with many places staying largely dry.
Forecaster Claire Austin said: "The South East will get thunderstorms on Sunday and that's where the rain will be most torrential.
"The rain will then push northwards across England and Wales and then should clear eastwards overnight.
"Monday will see more sunny spells with temperatures reaching highs of 20C in the south and 18 to 19C further north."
Revellers attending the Notting Hill carnival have been warned to expect showers, while rain is also expected to hit the Leeds Festival over the weekend.