Luton airport reopened to departing flights on Monday evening (July 18) after high temperatures caused a defect in the runway, forcing a temporary halt to services.
All incoming and outgoing flights were suspended shortly after 3pm so engineers could begin repairs on the runway.
Departures were restarted at 5.40pm with arrivals resuming shortly after 6pm.
However, passengers travelling to the airport on Tuesday face rail disruption because of the heatwave.
The airport website said no Thameslink or East Midlands Railway service will run on the Midland Main Line between Bedford and St Pancras International/London Blackfriars on Tuesday (July 19).
To the south of the Thames, Thameslink services to Brighton and Sevenoaks will now terminate at London Blackfriars. Thameslink services to Rainham will be suspended.
Commenting on the temporary closure, Guy Hobbs, editor of Which? Travel, said: “If your flight is cancelled because of the heatwave, you will be entitled to a refund or rebooking, including with other carriers if necessary.
“However, you are unlikely to be owed additional compensation as extreme weather is considered an extraordinary circumstance, outside of the airline’s control.”