Holidaymakers travelling to or from Heathrow and Gatwick Airports are being urged to “plan ahead” as part of the M25 closes for the third time this weekend.

The RAC is advising people to travel “earlier than usual” if their journeys will be affected by National Highways shutting the motorway between Junctions 10 and 11 in Surrey from 9pm on Friday to 6am on Monday.

This will be the third of five weekend closures of the motorway – which encircles London – as part of a £317 million project to improve Junction 10.

Motorway vehicles will be directed along a diversion route on A-roads.

Among the people affected will be many of those travelling to, from and between the UK’s two busiest airports, Heathrow and Gatwick.

It could also disrupt the journeys of music fans heading to and from London for festivals such as Wireless and British Summer Time, and football supporters travelling to watch the final of Euro 2024 with friends or at public screenings.

RAC breakdown spokeswoman Alice Simpson said: “Following two successful M25 closures with no significant delays, there’s no reason why this weekend can’t go smoothly too, providing drivers plan their journeys well in advance and follow the official diversion routes.

“While anyone attending a festival in the city centre is likely to have an easier journey by train and Tube, there are of course trips, such as going to the airport, where it’s far easier to travel by car, especially if you’re loaded with luggage.

“We’re asking holidaymakers to ensure they plan ahead, which means checking their route before they set off, leaving even earlier than usual and, importantly, making sure their vehicles are road ready by checking the oil, coolant and tyres to give themselves the best chance of avoiding a breakdown.”

Chris Wood, AA Patrol of the Year, said: “With potential for an upturn in the weather forecast and many football fans hoping to visit friends to cheer on their national team, it’s likely to be incredibly busy in and around London, particularly the M25 Junctions 10 to 11.

“We advise drivers to plan their journey accordingly, avoiding the west side of the M25 if possible, but if not to expect delays and stick to the detour routes.”

There were fears of severe congestion on diversion routes ahead of the first two closures in March and May, but many drivers followed advice to avoid the area, meaning long hold-ups were avoided.

National Highways senior project manager Jonathan Wade said: “The previous two closures have gone well, with significant progress being made during both.

“We would urge all drivers to follow the official diversion route as this is the best chance of reaching your destination in good time.

“Please ignore your satnavs and follow our diversion route instead.”

National Highways is concerned that satnavs could direct some drivers on to minor roads after leaving the M25, creating gridlock in residential areas.

Shutting the motorway this weekend will enable the construction of a new bridge near Junction 10.

The March closure was the first planned daytime shutdown of the M25 since it opened in 1986.

The project, due to be completed in summer 2025, will increase the number of lanes at Junction 10, which is one of the UK’s busiest and most dangerous motorway junctions.

Between 4,000 and 6,000 vehicles normally use the M25 between Junctions 9 and 11 in each direction every hour from 10am until 9pm at weekends.

The final two weekend closures as part of the project will take place later this year.