East Midlands Railway tells passengers 'do not attempt to travel' from Corby, Kettering and Wellingborough on Tuesday
and live on Freeview channel 276
But it warned: “Journeys will take twice as long as normal and return services are likely to be cancelled.”
A spokesman said: "Temperatures are forecast to reach 40°C. As the track is typically 20 degrees warmer than the air above, this extreme heat can cause the track to buckle and bend which poses a serious safety risk to our trains which travel at speeds between 100 and 125 miles per hour.
“To keep everyone safe, a speed limit of just 60mph will be in place between Sheffield, Nottingham and Bedford. Speeds will be limited further to just 20mph between Bedford and London.“As such, we strongly urge customers not to travel with East Midlands Railway. Journeys will take twice as long as normal and return services are likely to be cancelled.”
There will be no Connect360 services from Corby all day.
Forecasters expect a record-breaking day with the UK’s maximum recorded temperature of 38.7°C set in Cambridge in July 2019 likely to be exceeded in multiple locations.
County weather-watchers @NNweather say temperatures in the county forecast to be a hot 30°C by 9am with highs of 40°C likely this afternoon.
A first-ever Met Office red alert for extreme heat bringing a danger to life is in force for the Midlands.
Thameslink, which also uses the Midland Mainline between Bedford and London, also cancelled all its services north of the capital.
The decision came after Network Rail closed the East Coast Mainline from King’s Cross on safety grounds when rails buckled in Monday’s heat near Cambridge.
London Northwestern Railway has an emergency timetable in operation on its routes between London, Northampton and Birmingham.
Tickets for travel on Tuesday can be used on other days and if a journey has been disrupted by the weather customers may be entitled to a refund.