The public are being urged not to travel on the railways unless journeys are essential, as temperatures are set to soar even higher.
There is likely to be significant disruption to rail services across the North West due to the forecast high temperatures and red weather warnings in place.
Avanti West Coast has urged train passengers to travel only if it is “absolutely necessary” from Sunday until Tuesday.
The company said an amended service is currently running with far fewer trains, and those that do run will be subject to extended journey times and possible delays, due to imposed speed restrictions.Those with tickets dated Monday 18 or Tuesday 19 July who choose not to travel are entitled to a full refund via their point of purchase.
Alternatively, their tickets will be valid on Wednesday 20 or Thursday 21 July.
Meanwhile Merseyrail say the extremely high temperatures are causing a number of heat related problems to Network Rail track and equipment.
As a result, they say the number of Merseyrail trains running and journey times will be seriously affected.
Additionally, some routes will be closed completely.
There are no trains running between Kirkby and Liverpool Central due to hot weather conditions.
On the West Kirby and New Brighton lines, services will only run between Birkenhead North and Liverpool city centre with a 15-minute frequency.
No rail replacement buses will run.
Chester and Ellesmere Port services will only run between Rock Ferry and Liverpool city centre again with a 15-minute frequency and no rail replacement buses will run.
A 15-minute service will operate on the Southport to Hunts Cross line. There will be a limited service at the Bank Hall, Hightown, Hall Road and Hillside stations which will have a 30-minute service.
On the Hunts Cross line, services will start and terminate at Liverpool South Parkway. Rail replacement buses will continue to run between Liverpool South Parkway and Hunts Cross stations.
On the Kirkby line no train services or rail replacement buses will run.
On the Ormskirk line a normal service will operate.
All of these changes will be in place from the start to end of service on Tuesday 19 July.
Zoe Hands, Chief Operating Officer at Merseyrail said, “We apologise to Merseyrail passengers for the reduction of some services, this is due to a number of heat related issues with the infrastructure which mean our trains are unable to operate as normal.
“If you do have to travel, please remember to take water with you and to leave more time for your journey as disruption is possible.
“We are confident that services will return to normal from Wednesday onwards”.
Kara Wood, Head of Performance and Customer at Network Rail’s North West route, said:"We're sorry to announce that due to the unprecedented heatwave forecast on Tuesday, we're restricting some services on the Merseyrail network as a safety precaution.
"The predicted high temperatures could cause track temperatures to reach more than 50°C.
"When steel becomes very hot, it expands and rails can bend, flex and, in serious cases, buckle. These could lead to some trains being delayed, cancelled or stranded.
“In this extraordinary heat, rail passengers are being asked to only travel if absolutely necessary."
People who are still travelling are advised to take a soft drink or water.
Merseyrail staff will be on hand to help passengers who may struggle with the heat.
Any passengers who are feeling unwell while on a train should get off at the next stop and request help from station staff.
Water will be available at all staffed stations for passengers who are feeling unwell.
However, National Highways reported no current issues or concerns on roads and motorways in the North West.
There's no service on the trams between Bury and Manchester Victoria Mel Clarke, Customer Service Director for Operations at National Highways, said: "Our motorways and major A roads are highly resilient to extremes of weather.
"Around half of our network has an asphalt mix surface that can withstand high temperatures and half has a low noise surface, which has an even greater resistance to heat."Both types of road surface are suitable for use in very hot weather and in a changing climate. The design and build standards we apply to our roads are considered best practice and adopted in other countries around the world."