Greater Anglia Railway has warned against using its trains early next week (July 18 and July 19), due to the expected heatwave.
Passengers have been warned of wide-spread disruption and short-notice cancellations.
Many journeys are expected to take longer than at usual times, with trains travelling at slower speeds and on alternative routes in some cases.
Notably, the Ipswich to Peterborough service will terminate and start at Ely between 12.00 noon and 8.00pm.
A spokesperson for Greater Anglia said: "Greater Anglia is advising people to avoid travelling by rail on Monday (July 18) and Tuesday (July 19), when temperatures are forecast to be extremely high and widespread disruption to rail services is likely across the region and the rest of the rail network.
"Network Rail is imposing speed restrictions across the whole of the Greater Anglia network to ensure the safe running of trains and in a bid to protect the rail infrastructure from damage."
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