The UK has received its first ever Red Extreme heat warning as temperatures soar across the country over the next two days.
The Met Office issued the warning, calling it "exceptional" and stating that we are likely to see record-breaking temperatures this week.
A Level 4 UK Health Security Agency Heat Health Alert has been issued for Monday Jul 18 and Tuesday 19.
With heat levels rising to nearly 40 degrees in London and in the South East, the red weather warning will likely cause delays to all transport, including our train networks.
But what temperature causes the UK's train tracks to buckle and what procedures are in place to prevent train services going off the rails?
What temperature will cause train tracks to bend and buckle?
Network Rail has said that the tracks remain "stress-free" at temperatures around and below 27C; anything above that can cause strain.
With weather expected to be 13C above that over the next couple of days, tracks could be at risk of expanding and buckling.
Steel rails tend to sit around 20C above the surrounding air temperature due to how easily they absorb heat, meaning surfaces on the tracks could rise to 60C.
What is being done to prevent train tracks overheating?
'Stressing' is a method used by rail workers to try to reduce heat on the tracks.
By painting the rails white, less heat is absorbed, cooler levels can be maintained and rail lines are less likely to bend or buckle.
Will there be delays and cancellations?
Network Rail have said delays and additional time on journeys will vary across the UK, but people should expect "significant delays with a high likelihood of cancellations".
Avanti West Coast has advised passengers they should only travel if absolutely necessary, due to train crew shortages and heat weather warnings.
Delays and cancellations are said to be particularly prevalent on longer routes with large stretches of exposed train tracks that don't have shade.
What to expect if you are travelling
Along with delays and possible cancellations, all train companies have advised passengers to make sure they stay hydrated to cope with the heat.
Some have even suggested taking a hand-held fan, as temperatures on the trains themselves could cause discomfort.
If any passengers start to feel ill, Network Rail have suggested disembarking at the next station and seeking assistance as soon as possible.
If you do have to travel, remember to bring plenty of water.
