The M25 will be shut in both directions south of Heathrow between junctions 10 and 11 from 9pm on Friday 15 March until 6am on Monday 18 March owing to works on the Wisley Interchange.
While a signed diversion will be in place, both Heathrow and British Airways have warned routes to the airport will be "very busy".
The Airline bus services between Heathrow and Gatwick and RailAir services to Heathrow from Reading, Guildford, Woking and Watford will be operating to amended timetables.
"Due to planned works, the M25 will be shut between junctions 10 and 11 from 9pm on Friday 15 March until 6am on Monday 18 March," said Heathrow. "A diversion will be in place, however, journeys are expected to take much longer than usual.
"Passengers planning to use this part of the M25 should allow for extra time when travelling to Heathrow during this period. For more information, please visit National Highways’ website.
"Passengers using public transport should also be aware that The Airline (between Heathrow and Gatwick) and RailAir (RA2) will be running amended timetables over this weekend, please check with your operator for the latest information."
British Airways added: "The roads will be very busy so please plan ahead and allow extra time for your journey."
RailAir said: "Due to the closure of the M25 between junctions 10 and 11, an emergency timetable for our RA2 service will be in operation on Saturday 16 March and Sunday 17 March 2024. Passengers should allow extra time for their journey, as the exact conditions cannot be predicted. We are sorry for the inconvenience."
