Services operating between Scotland and London have been cancelled - including those between Glasgow and the English capital - while repairs are carried out.
The recent heatwave, which saw temperatures hit over 40 degrees in parts of Britain, caused damage to the rail infrastructure.
While Network Rail said that staff had been working “thoughout the night” to fix some of the damage, there is still much work to do.
London Euston train station posted on social media: “There are currently no trains from London to Scotland.
“Check before you travel to a station today @nationalrailenq. Our teams worked all night and are still fixing faults caused by extreme heat.”
Network Rail Scotland added: “Network Rail colleagues in England have been working through the night to repair damage caused by the extreme heat yesterday.
“This has been a very challenging 24 hours. There is still a lot of work to do, but the teams are working hard to make those repairs.”