Rail companies in Lincolnshire are urging their passengers to not travel today while temperatures look set to soar over 35 degrees celsius.
LNER and East Midlands Trains have both said that the extreme heat will lead to widespread disruption as trains could be delayed at short notice.
Steel rails could top 50C in the sun – leaving the risk of buckling under pressure.
In the summer, the track can get up to 20 degrees hotter than the air temperature.
Any tickets bought for Thursday, July 25 will be valid for Friday, July 26 so commuters will not miss out on their journeys.
People who choose not to travel may be entitled to a full refund.
A spokesperson for LNER said: “We are expecting high temperatures today. As a result, a speed restriction will be in place between London King’s Cross and Peterborough all day.
“We are running a reduced timetable today and we expect our trains to be extremely busy. We encourage customers to avoid travel today.”
East Midlands Trains have also said that they will be following speed restrictions all day on July 25.
“Our focus is to ensure our trains and our stations can be safely used by our customers,” a spokesperson for EMT said. “Speed restrictions are being introduced across wide parts of the UK rail network as a result of the record UK temperatures forecast for today.
“With high track temperatures and the speed restrictions we have to run a significantly reduced timetable.”
LNER customers can check whether they are eligible for compensation on their website by clicking or tapping here.
Rob McIntosh, Managing Director of Network Rail Eastern, said: “Passenger safety will always be our number one priority. And with forecasts of unprecedented temperatures, we have to take action to keep people safe.
“Reducing speed limits will mean fewer services and busier trains on our main routes into and out of London.
“So I’d like to ask all passengers to think about whether their journey is really necessary and, if it is, to make sure they plan well ahead.
“I’m sorry for the disruption this will cause, but it is essential to maintain the safety of the travelling public.”