The ferocious heat has buckled rail lines and caused widespread disruption.

Explaining why, Grant Shapps, the transport secretary, says rail infrastructure in the UK is not built to withstand extreme temperatures - both very hot and extremely cold - and that although much of it is being upgraded, that process will take decades.

"Many of the hottest days ever recorded have come in the last 10 to 15 years, so we're going to see this more," Shapps told Sky News.

This means that the problems we are experiencing during this heatwave are going to repeat themselves for decades to come, he added, saying that "millions of miles" of tarmac on the roads will have to be replaced too.

Simon King
BBC weather presenter and meteorologist

After provisionally the warmest night on record, it’s already very warm outside.

Temperatures are rising quickly and as at 08:00 BST were hitting 30C in some spots - a good five Celsius higher than this time yesterday.

Temperatures will exceed those reached yesterday, with the national record under threat.

Temperatures of over 40C are expected in an area around South Yorkshire, Lincolnshire, the East Midlands and towards Suffolk.

The UK appears to have had its hottest overnight temperature on record last night, with an increase of 2C on the previous figure.

A temperature of 25.9C was recorded in Emley Moor in West Yorkshire, according to provisional figures.

The next highest temperatures were 25.8C in Kenley, Surrey, 25.8C Jersey Airport, 24.5C Aberporth in Ceredigion.

The previous record was 23.9°C.

However, absolute minimum temperatures don’t come in until later this morning so we’ll need to wait for official confirmation.

The Welsh record for an overnight temperature of 22.2C may also have been broken. We'll keep you updated.

For Britain's farming communities, this week's soaring temperatures are only adding to existing challenges they've been facing.

One Lincolnshire farmer, Andrew Ward, told BBC Radio 4's Today programme he was harvesting his wheat crop weeks early due to the shortage of rainfall this year.

He explains there has been 70mm (2.8in) rainfall since the beginning April on his farm - barely over half of the 134mm that fell the year before - which wasn't even a particularly wet year.

Fertiliser costs have tripled and diesel doubled, he says, adding: "This time of year, obviously we've got a lot of machinery out running in the fields and the amount of fuel we use is huge."

The lack of rainfall and early harvest could see yields down, in a market where food prices are already climbing over energy cost rises and supply issues driven by the war in Ukraine.

Lower yields and rising prices are also affecting livestock farmers, with the cost of feed and straw up significantly, Ward adds.

Image source, Reuters

Network Rail has issued a "do not travel" warning, external today affecting services travelling through the "red zone" of the Met Office's weather warning.

No Thameslink or Great Northern services are scheduled to run north from London all day, and there will be no services from London King's Cross or on the East Coast Main Line. About 220,000 passengers a day would normally pass through the station using that line.

There will also be only limited services from London Euston, London Marylebone and on the East Midlands Railway.

Network Rail said that the forecast temperatures for parts of the network are higher than the design limits for track and overhead line equipment, with speed limits in place on many lines.

A massive backlog of passengers have been disrupted after Luton airport closed its runway due to high temperatures. The airport reopened after 18:00 BST last night.

In London, several Underground lines are running with delays or are part suspended - check the latest updates here, external.

Image source, .

Peterborough, Caernarfon and Swindon are among the areas projected to reach 32C (90F) by 10:00 BST, according to forecasts.

By 16:00, Lincoln, Cambridge and Huntingdon could see 40C, and areas in the corridor around the A1 and M1 roads may even surpass this.

The peak temperature around the country reached on Monday was 38.1C in Suffolk, making it the third-hottest day on record and the hottest of the year so far. The overall UK record of 38.7C was set in 2019.

In Wales, the heat record was provisionally surpassed, when a temperature of 37.1C was measured in Hawarden, Flintshire

Scotland and Northern Ireland also saw their warmest days of the year, with temperatures of 31.3C and 31.1C recorded in Aboyne, Aberdeenshire and Derrylin, Co Fermanagh respectively.

For Jorda and her two daughters, who live in west London, their flat has been over 30C (86F) before midday for days. Her small, concrete balcony gets no shade and, even if it did, would be almost unusable because of exhaust fumes, dust, traffic noise and other pollution.

Instead, they are forced to shelter from the sweltering temperatures in her bathroom. Jorda also has severe asthma, which is exacerbated in hot weather and has led to frequent hospital trips after attacks, forced her to give up work and limited her ability to leave home.

While severe heat affects us all, a BBC investigation has shown people living in areas with high proportion of people on low incomes or out of work are most at risk from severe heat.

Image source, .

Analysis of satellite data from 4 Earth Intelligence and figures on relative poverty in England, Scotland and Wales, suggests people in deprived areas are more than twice as likely to live in places which are significantly hotter than neighbouring places.

The difference is down to a phenomenon known as the urban heat island effect, where buildings and roads absorb and retain heat and become significantly hotter than surrounding areas with shade or green space.

Read more of our investigation here.

Image source, .

Image source, Reuters

The UK Health Security Agency has issued some handy tips for staying safe., external

Here are some of the main ones:

• Look out for those who may struggle to keep themselves cool and hydrated, such as older people, those with underlying conditions and those who live alone
• Stay cool indoors by closing curtains on rooms that face the sun, and remember that it may be cooler outdoors than indoors
• Drink plenty of fluids and avoid excess alcohol
• Never leave anyone in a closed, parked vehicle, especially infants, young children or animals
• Check that fridges, freezers and fans are working properly
• Try to keep out of the sun between 11am to 3pm, when the UV rays are strongest
• Walk in the shade, apply suntan lotion and wear a wide-brimmed hat if you have to go out in the heat
• Avoid physical exertion in the hottest parts of the day
• Make sure you take water with you if you are travelling

Nick Miller
BBC Weather

The extreme heat is coming during a prolonged period of drier than average weather, with July producing very little rainfall so far in England and Wales.

Up to 15 July, only around 6% of an average July’s rainfall had fallen across England and Wales and that figure falls to 1% for south-east England.

If you think things are looking parched out there, this heat will only make things worse.

The BBC's Ben Rich talks us through the weather, with temperatures expected to reach up to 42C (107.6F).

Image source, Getty Images

With today expected to be the hottest on record in the UK, here are some things you can do to keep the heat down indoors:

• Let in cool air - open the windows overnight or for a couple of hours in the early morning
• If you can, open windows on the opposite sides of the home to encourage airflow
• Before temperatures rise, close all windows, external doors, blinds and curtains to keep out hot air and sunlight
• Use a fan and consider placing a bowl of ice in front of it
• Avoid cooking for long periods or running appliances that generate heat
• Reduce humidity, which can bring on heat exhaustion, by wiping excess water from surfaces and moving indoor plants outside

Read more.

Image source, PA Media

We're now restarting our live coverage of the UK heatwave - forecasts suggest temperatures could reach 42C.

A red extreme heat warning covers much of central, northern, and south-east England.

And Network Rail has issued a "do not travel" warning for people travelling through the "red zone" of the Met Office's weather warning.

Stay with us for updates on the forecasts, news on disruption, official advice, and tips on how you can stay safe in the heat.

We are pausing our live coverage here, but before you go, do read these top tips on how to get a good night's sleep, as we prepare for another night of high temperatures.

Read more here

Image source, Getty Images

Here's what happened on one of the UK's hottest ever days:

• The Suffolk village of Santon Downham recorded the hottest temperature in the UK on Monday at 38.1C (100.58F).
• Wales, meanwhile, recorded its hottest day on record with highs of 37.1C (98.78F) in Hawarden, Flintshire.
• London Luton Airport suspended flights for several hours after surface damage to the runway caused by heat.
• There were heavy delays and cancellations on the rail network too, with reduced timetables in place across parts of the UK.
• Several people have died after getting into difficulty in water, including a 16-year-old boy in Berkshire.

Image source, PA Media

We've heard lots about the heatwave and its effects, but what about the people helping those who are finding it all too much?

The UK's new Health Secretary Steve Barclay told MPs earlier that Britain's emergency services are experiencing a rise in 999 calls - and warned over increasing temperatures tomorrow.

"There's a time lag in the data because the highest point of the expected heatwave is actually going to be tomorrow afternoon," he said in the Commons, adding this was "the point of maximum concern".

NHS medical director Professor Sir Stephen Powis praised staff as he said "the overwhelming majority of NHS services are continuing to run despite the unprecedented heatwave".

With rising calls in mind, though, he advised using 999 as a last resort.

He said if "you or a loved one" begin to feel ill, "you can get advice and a referral to NHS services, if it is needed, through 111 online or from your local pharmacist, with 999 there for anyone who requires emergency care for a life-threatening condition".

Many rail operators ran heavily-reduced timetables on Monday - and the disruption looks set to continue on Tuesday.

There will be heavily reduced timetables on Avanti West Coast, CrossCountry, Great Northern and Thameslink services.

Meanwhile, LNER will run no trains from south of York and south of Leeds to London King’s Cross.

Chief spokesman for Network Rail Kevin Groves said journeys which normally take two hours could take more than four hours as emergency measures are brought in to prevent trains derailing.

The return to normal services on Wednesday will depend on any damage that the weather inflicts on infrastructure, Network Rail’s Jake Kelly told the BBC’s Today programme.

So the UK has experienced one of its hottest ever days and the Met Office is warning of worse to come on Tuesday. These were the highest temperatures today:

The current record UK temperature (38.5C in Faversham, Kent, in August 2003) looks certain to fall on Tuesday, with forecasters predicting the 40C barrier may be reached in London, and the mercury hitting a "crazy" 41C in Yorkshire.

Insaf Abbas
BBC News

We've been speaking to tourists exploring London to find out how they have been keeping cool in this heat.

In Trafalgar Square, one woman from Germany tells us she did not expect it to be so hot in the UK this week - in fact, she brought an umbrella with her as she assumed it would rain.

Meanwhile in London's Southbank, beside the River Thames, a family from the US say the weather is "pretty normal" for them.

"We're actually laughing about how big a deal it is here," they added.

They are keeping cool by eating lots of ice cream, drinking water and finding places with air conditioning.

Image source, SUPPLIED

We're still getting reports of the knock on effects of the runway closure that hit Luton airport earlier today. This picture taken within the hour is from Caitlin H. who's trying to catch a flight to Naples with friends.

She says some passengers were told to go to their departure gates but flights were not ready to take off. Staff are telling passengers to leave the departure gates again, she says.

The airport has apologised for the disruption, caused after the surface of the runway was affected by the extreme heat. The runway is back in action, but it looks like things are not yet quite back to normal.