Commuters are being advised to avoid travelling unless their journey is essential this morning as yesterday’s heatwave continues to cause chaos.
With temperatures hitting over 38C, the UK’s rail network struggled to cope with rails buckling and overhead cables being damaged.
The worst-affected train companies are Great Northern, Thameslink and East Midland Trains.
Thameslink will have a reduced ability to run trains, with half of its lines unavailable.
East Midlands trains between Sheffield, Nottingham, Derby and London St Pancras International are also affected.
‘East Midlands trains will be operating … on an emergency timetable due to the reduced number of lines available for trains to operate on,’ the company said.
‘East Midlands trains strongly urge you not to travel on the London St Pancras International / Nottingham / Sheffield route today.’
Services between Peterborough and Hitchin will not run until 7am.
In a statement, Network Rail said it had been ‘unable to completely fix the damage to the overhead wires between London St Pancras International and St Albans, and will continue to work on this on Friday night’.
It added: ‘Please check and replan your journey, as service information will be updated throughout the day.’
The weather is also causing difficulties to flights. British Airways announced that ‘severe thunderstorms are causing significant delays and cancellations to our operation in and out of London’.
Further travel chaos could be caused by thundery downpours prompted by the sweltering temperatures, with flash flooding and power cuts possible.
Speed restrictions on most commuter lines were imposed over fears steel tracks could buckle in the heat, while the conditions also led to overhead electric wires being damaged, blocking all lines between London and Luton.
Overhead wire failures also caused disruption between London and Watford, between Preston and Carlisle and in the Birmingham area.
Greater Anglia and Stansted Express services from London Liverpool Street are expected to be hit by delays until today, according to Network Rail Enquiries.
Commuters were dealt a further blow when they were told they could not claim compensation.
Thousands of people were left stranded yesterday during the evening rush hour as the temperatures caused havoc.
One passenger posted a video aboard a stationary London North Eastern Railway (LNER) service showing sweat-soaked commuters, including a man with a baby, desperately fanning themselves.
Another image shows a collapsed man being treated by medical staff outside the train.
Despite fresher conditions forecast for Friday, ‘disruption is likely to continue into the morning’, said Network Rail’s network services director Nick King.
Mr King said: ‘Our teams have been working flat out to fix the issues, however we are sorry that disruption is likely to continue into the morning.
‘We are advising passengers to check with their train operators or the National Rail Enquiries website before travelling.’
Travellers were urged to check the website before setting off on their journeys.
A yellow warning for thunderstorms has been issued for most of England except the South West, and parts of Scotland until 4am on Friday.
Much of the country is forecast to experience more balmy temperatures of around 23C to 25C (73.4F-77F) throughout the day, according to the Met Office.
Chief meteorologist Steve Willington said: ‘We’ll continue to see thunderstorms breaking out this evening and overnight across wide areas of the UK.
‘Also tonight it’s going to be very warm across central, eastern and south-eastern parts in particular as temperatures fall no lower than 23C to 24C in places, which could see further temperature records broken.’
The dangers of cooling off in lakes, rivers and the sea were highlighted by emergency services after the bodies of three people were pulled from water after they reportedly got into difficulty swimming during the week’s heatwave.
Two bodies were found during police searches in separate incidents on the Thames and the body of a man was pulled from the water at Cotswold Water Park, near Cirencester, on Tuesday.
The Eastbourne Herald also reported a swimmer died on Friday after being pulled from the sea in Pevensey, East Sussex.
Searches continue for someone seen in the River Thames near Waterloo, Scotland Yard said.
The Met Office said a new record temperature for the month was set at 38.1C in Cambridge on Thursday afternoon, beating the previous record of 36.7C set in Heathrow in 2015.
But the country will see more familiar conditions return into the weekend, with the weather becoming less settled and an increased chance of rain for many eastern and north-eastern areas.
The Government’s advisory Committee on Climate Change has warned the UK is not prepared for the increase in heatwaves that is expected with global warming.