Four million sun-seekers are expected to be on the move, travelling to coastal resorts, festivals and airports. Forecasters predicted temperatures of 27C (81F), with the south of England enjoying the best weather.
The M6 at Birmingham was among the first to experience traffic jams yesterday morning, with congestion developing on other routes across the country by late afternoon.
Bernard Jenkin, the opposition transport spokesman, used the expected queues as an opportunity to criticise the Government, saying scrapped by-pass and improvement schemes had added to the misery. "The list of expected hot-spots ... contains many roads that were due to be improved. But Labour reduced the roads programme from 140 scheme to just 37. Britain's motorist are getting a raw deal," he said.
The more unusual events expected to draw crowds at the weekend include a bog snorkelling and mountain bike leaping championship at Llanwrtyd Wells, Wales.
Shark-spotters were heading for Cornwall after reported sightings of a great white off Padstow.
In London two million revellers were expected at the Notting Hill Carnival over the next three days.
Others events across the country include rock festivals in Reading and Leeds, the Edinburgh Festival and Tattoo, and a town and country event at Kenilworth, Warwickshire.
Airports were steeling themselves for an influx of 1.5 million passengers over the longweekend break, with Mediterranean resorts proving the most popular.Reuse content