Rail and air passengers have been warned to expect more delays after record-breaking temperatures caused travel chaos on Thursday.
Rail companies feared rail lines would buckle – but it was overhead cables sagging which caused problems.
East Midlands Trains advised people not to travel on services in and out of London St Pancras on Friday, while other firms have reduced timetables.
There are also delays and cancellations at London airports.
The disruption to flights on Thursday evening and into Friday morning was caused by storms across Europe.
In the early hours of Friday, British Airways said “severe thunderstorms” had caused “significant delays and cancellations”.
Friday is expected to be cooler than Thursday, with temperatures ranging from 23C to 25C in most areas (73F to 77F), rising to 27C in south-east England.
During the day it will be mostly dry but rain is expected to develop across northern and eastern areas of the UK overnight.
Speed restrictions across parts of the rail network on Thursday prevented lines from buckling in the heat, but damage to overhead lines left some commuters stranded in London on Thursday night.
Despite working “flat out” to repair the damage, Network Rail said disruption was likely to continue into Friday morning and advised passengers to check with their train operator before travelling.
- East Midlands Trains urged passengers not to travel on its London St Pancras / Nottingham / Sheffield route, and an emergency timetable is in place
- Thameslink services – which operate on part of the same route – will also be disrupted
- Greater Anglia and Stansted Express services will be disrupted until 10:00
- All operators on the East Coast Main Line will be disrupted until 10:00
- In Birmingham, passengers on all routes have been told to expect delays until 10:00
Many operators said tickets for Friday could be used the following day, and offered compensation to season ticket holders who did not travel on Thursday.
However, Govia Thameslink Railway, which operates trains in south-east England, said passengers with an annual pass would only be entitled to compensation if they attempted a journey on Thursday and were delayed – despite it urging customers to avoid travelling where possible.
Anthony Smith, chief executive of independent watchdog Transport Focus, said: “All passengers told not to travel due to extreme weather should be entitled to claim compensation.”
Thursday saw the UK’s second hottest day – and hottest July day – on record, with temperatures reaching 38.1C (100.6F) in Cambridge.