Brits have been warned of travel chaos next week during the extreme 40C temperatures, as Network Rail urged passengers to stay away during the national emergency.
Earlier today The Met Office issued its first ever red warning for exceptional heat next Monday and Tuesday for swathes of the country.
The mercury is feared to burst through the highest ever set - 38.7C in 2019 - and possibly rising as high as 40C.
As a result Network Rail has warned people to travel only if absolutely necessary, as speed restrictions will need to be implemented on tracks, and TFL revealed its Overground service will be reduced.
Jake Kelly, the train firm’s system operator group director, said: “Rail passengers in England and Wales should only travel if necessary on Monday and Tuesday as there will be delays and cancellations to train services due to the unprecedented heat we’re expecting.
“The wellbeing of our passengers is our first priority so we’re asking all passengers who decide to travel to take time to prepare before leaving the house.
“Remember to bring a water bottle with you, along with whatever else you need to keep yourself well in the heat.
“Water bottles can be refilled for free at most Network Rail’s managed stations.
“Journeys will take significantly longer and delays are likely as speed restrictions are introduced to keep passengers and railway staff safe, so make sure to allow considerably more time to complete your journey and be prepared for very hot conditions.”
London mayor Sadiq Khan added commuters should make "substantial changes" to their routines and for Londoners to "look after one another" during the unprecedented conditions.
It comes as Downing Street earlier said restrictions may be required as contingency plans with the temperatures set to rise.
A No 10 spokesman said discussions with sectors including the NHS will “continue to work closely with all of those sectors over today, through the weekend and into early next week”.
He added: “Specialist teams from Network Rail and TfL (Transport for London) will continue to monitor the impact of high temperatures to try and make sure they can keep services running safely and reliably for customers.”
“It may be the case that speed restrictions are likely to be put in place on some parts of the network next week to manage the hot weather and to avoid any potential damage.
“DfT (Department for Transport) are engaging with port operators and highways agencies, as well as the police, to make sure plans are in place particularly in places where you may see queuing.”
However, Downing Street has not issued work from home guidance during the heatwave.
The Met Office expects "population-wide" health effects, which will affect not just those most vulnerable to extreme heat "leading to serious illness or danger to life".
There is also a high risk of heat-sensitive systems and equipment overloading, potentially causing power loss to essential services such as water and mobile phone services, while speed limits are likely to be imposed on railways to protect tracks.
Met Office chief meteorologist Paul Gundersen, said “Exceptional, perhaps record-breaking temperatures are likely early next week, quite widely across the red warning area on Monday, and focussed a little more east and north on Tuesday.”
Penny Endersby, Met Office chief executive, added in a video shared online: “The extreme heat that we’re forecasting right now is absolutely unprecedented.
“We’ve seen when climate change has driven such unprecedented severe weather events all around the world it can be difficult for people to make the best decisions in these situations because nothing in their life experience has led them to know what to expect.
“Here in the UK we’re used to treating a hot spell as a chance to go and play in the sun.
“This is not that sort of weather.
“Our lifestyles and our infrastructure are not adapted to what is coming.
“Please treat the warnings we are putting out as seriously as you would a red or amber warning from us for wind or snow and follow the advice.
“Stay out of the sun, keep your home cool, think about adjusting your plans for the warning period.”
