Rainy conditions and the start of the school half-term holidays are likely to lead to the worst traffic congestion of the year so far tomorrow, it was predicted today.

The gloomy forecast came from the AA which warned that queues were likely to build up on major routes from 10am tomorrow.

With showers expected tomorrow and heavier and more general rain across the UK on Saturday, families are flocking abroad, with Tenerife, Turkey and Egypt among the most-popular destinations.

Motoring groups, the Highways Agency and safety campaigners also warned drivers to take extra care, especially as darker evening will begin when the clocks go back on Sunday.

The AA said the last chance of a break in the sunshine before Christmas was likely to cause gridlock on roads to airports and on other major routes tomorrow.

A spokesman went on: "We're likely to get the worst traffic congestion of the year so far, with the heaviest traffic from 3pm tomorrow.

"The roads will also be very busy on Sunday November 1, when people head home."

Among roads likely to bear the brunt of the congestion are the M25, the M6, the A303 through Wiltshire and Dorset, the M5 to south west England and the M55 to Blackpool.

The Highways Agency, which is responsible for England's motorways and major A roads, said major routes would be busier than usual tomorrow evening and also during the day and evenings of other days during the half-term week.

Steve Crosthwaite, head of the agency's national traffic control centre, said: "The best thing people can do is plan their journey before they set off. They can easily check if there are any delays on the route ahead and leave extra time for their journey or find another route if necessary."

Tom Mullarkey, chief executive of the Royal Society for the Prevention of Accidents, said: "We urge road users to remember the responsibility they have for the safety of those around them.

"Pedestrians and cyclists who, from Monday, may be travelling home from work or school in the dark should ensure they can be seen, and motorists need to watch their speed and keep an extra look out for vulnerable road users."

The Co-operative Travel company said a dip in holiday costs had boosted half-term trips to the Egyptian resort of Sharm el Sheikh, where bookings were 142 per cent up on this time last year.

Tenerife is the most popular half-term destination for Britons, with the Turkish resort of Dalaman second and Sharm el Sheikh third.

Co-operative Travel added that the weakness of the pound against the euro had led to Majorca losing its normal half-term destination top spot, with the Spanish island dropping to fourth.

Other popular destinations for Britons this half-term include Lanzarote, Larnaca in Cyprus, Spain's Costa Blanca and the Portuguese Algarve.

Research from Santander Cards, part of Santander Bank which includes the Abbey and Alliance & Leicester businesses, showed that half-term breaks were 104 per cent more expensive on average than holidays taken a week later.

It said families travelling to Lanzarote from Gatwick airport were having to pay a package of £5,485 between 24 and 31 October, compared with just £1,572 a week later.

Emma Roberts, director at Santander Cards, said: "Our research shows that parents with children of school age face a massive premium if they want to take their children away during the half-term break.

"It's not surprising therefore that some families would rather take their children out of school during term time and risk censure from their children's school than be hit by such staggering premiums."

Low-cost carrier easyJet said it was flying around 750,000 people off to foreign destinations.

Top destinations for a half-term holiday, according to the airline, are the Spanish resorts of Alicante, Barcelona and Malaga.