Temperatures in the south east of England are set to eclipse the rest of Europe, which is also experiencing widespread hot weather - Met Office

Parts of Britain are hotter than anywhere else in Europe with 36C (96.8F) forecast for Thursday, as the heatwave forces the cancellation of trains amid fears tracks will buckle.

With the country just one stage away from a national emergency being declared, the Met Office predicts the UK might experience its hottest day on record with temperatures possibly exceeding 38.5C (101F) on so-called Furnace Friday.

Commuters already battling difficult travelling conditions are being hit by a series of train cancellations and delays, as speeds are reduced to prevent tracks from buckling. Greater Anglia cancelled 13 services on Thursday - including seven rush-hour trains out of London.

And passengers using cross-Channel Eurotunnel services face delays of up to five hours after air-conditioning units failed on trains amid sizzling temperatures.

Meanwhile, air quality warnings have been issued for London due to a mix of toxic air, extreme highs, emissions from the continent and a lack of cloud. Young people, the elderly and those with lung or heart problems are advised to reduce strenuous exercise.

Commuters Brian Donovan and a woman on a South Western Railway train endure hot conditions on Thursday Credit: Jeremy Selwyn/Eyevine

Large parts of northern Europe are gripped by extreme hot weather, but a Met Office map shows the south east of England is forecast to be hotter than anywhere else on the continent.

The mercury is set to hit 36C (96.8F) on Thursday, which is already the hottest day of the year so far after Heathrow reached 35C (95F).

It isn't just the UK experiencing the #heat at the moment ��️ much of Europe is too pic.twitter.com/A42Jv2636S — Met Office (@metoffice) July 26, 2018

Temperatures are due to rise further to at least 37C (98F) and beyond in the south-east on Friday, triggering a thunderstorm warning in the afternoon with the risk of flooding, difficult driving conditions and power cuts.

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But the Met Office said Friday could potentially beat the highest temperature ever recorded in Britain, which was 38.5C (101F) at Faversham, Kent, in August 2003. The hottest July day on record is 36.7C in 2015.

Video: How Britain is coping (or not) in heatwave

The forecaster's yellow weather warning for torrential downpours, hail and strong gusts on Friday afternoon and evening has been extended to cover the south east of England, as well as northern and eastern parts of the country.

The Met Office and Public Health England have issued a level three heat health watch alert covering a large part of England, warning people to stay out of the sun until Friday and keep their homes cool.

Britain is just one stage away from a national emergency, which will be triggered if healthy people start becoming seriously ill - but visits to the NHS Choices website have already risen by 450 per cent as people struggle with heat exhaustion and sunstroke.

From green to brown in a month: Satellite images show how Britain has changed

Trains cancelled and delayed to prevent tracks from buckling

Rail journeys are being disrupted by the hot weather as train speeds are reduced to stop tracks from buckling.

Cutting the speed of trains reduces the forces they exert on the track, making it less likely to buckle. A buckled rail usually causes delays and cancellations as the line needs to be closed while engineers wait until the temperature drops to carry out repairs.

Thousands of commuters were left furious after Greater Anglia cancelled multiple services on Thursday.

Many Chiltern Railways trains between London and Oxford are being rescheduled and speed restrictions have also been introduced by Northern.

Meanwhile, temperatures on the Central line of the London Underground have hit 40C- above the 30C maximum temperature at which cattle can legally be transported.

Video: The Telegraph takes the temperature of the Tube

Overheated passengers mocked officials who reassured them that air conditioning will be installed - in 12 years.

Responding to complaints, the official Central line Twitter account replied: "Hi we're aware of the heating issues. We've made improvements to the ventilation systems on the current fleet.

"New trains are coming in early 2030, under the Deep Tube Upgrade Program which will be delivered with full air cooling systems."

Eurotunnel passengers face five-hour delays as air conditioning fails

Passengers using cross-Channel Eurotunnel services face delays of up to five hours after air-conditioning units failed on trains amid sizzling temperatures.

The English end of the Folkestone-Calais link was worst affected, with travellers forced to queue for up to 90 minutes just to check in and a further three and a half hours for the next available slot, according to the operator.

Footage posted on social media showed long queues of cars, caravans and lorries.

Only meant to leave at 1050! Eurotunnel staff have been great in tough and hot conditions. Now getting beyond a joke! Here's hoping train c gets going soon! #eurotunnel#traincpic.twitter.com/1dAKTrWI8U — rockyuk83 (@rockyuk83) July 26, 2018

A Eurotunnel spokesman said: "Due to the exceptional and prolonged temperatures, some of the air-conditioning units on board our shuttles are struggling to produce sufficient cool air.

"Our priority is customer well-being and safety so we are unable to board vehicles to these carriages."

If your planning on going to France today, don’t bother. 2 hours and still not passed check in. #eurotunnelpic.twitter.com/BOdicvRx8J — Andy Walker (@andy_walker21) July 26, 2018

It is one of the busiest weeks of the year for Eurotunnel as the start of many school summer holidays leads to a surge in families travelling to France.

Nurses 'becoming patients themselves' due to heat: Medics are 'exhausted, sick and dizzy'

Nurses have reported feeling exhausted, sick and dizzy as the hot weather raises temperatures in hospitals. One nurse was admitted to A&E with dehydration after working three 12-hours shifts in a row during the heatwave, the Royal College of Nursing (RCN) said.

Earlier this week, the organisation warned that patients and relatives were passing out and vomiting, with temperatures on some wards exceeding 30C (86F). It also said some nurses were not allowed to take water bottles on to wards.

Kim Sunley, national officer at the RCN, said: "Nurses are now becoming patients themselves due to the heat. We have heard from one member who ended up in A&E suffering from dehydration, after working 12-hour shifts back to back in temperatures exceeding 30C. Others have reported exhaustion, sickness and dizziness.

"This is not acceptable. Good patient care depends on nurses and clinical support assistants being well enough to perform their jobs effectively.

"It is vital employers adapt working practices to the heat. Both patients and nurses must have easy access to water, and all healthcare staff should be able to take regular breaks, preferably somewhere cool."

Fire brigade calls for ban on barbecues in parks

London Fire Brigade is calling for a temporary ban on barbecues in public parks after a record-breaking spate of grass fires in the tinder dry capital.

London Fire Commissioner Dany Cotton, who has written to all London councils suggesting the move, said: "I have attended a number of these large grass fires and it never ceases to shock me how many abandoned smouldering barbecues fire crews spot. In these arid conditions, barbecuing on dry grass is not just thoughtless, it's reckless."

She added: "It's only a matter of time before hot smoke and flaming debris catches nearby cars and houses and someone is seriously hurt."

We're getting tough on those starting grass fires - if you chuck a cigarette or match down on dry grass the chances are it could start a fire. Do you really want that on your conscience? https://t.co/qCj0OtR1bs#heatwaveukpic.twitter.com/qKIHW4FD1p — London Fire Brigade (@LondonFire) July 25, 2018

So far this year, London's fire crews have tackled six times as many large grass fires as the total number attended in 2017.

Barbecues are one of the main causes of grass fires, along with cigarettes and glass bottles.

Homes, offices, schools and transport systems ill-prepared for deadly heatwaves, MPs' report warns

Britain is ill-prepared to cope with heatwaves, a major report by MPs has warned. The Commons environmental audit committee said that adapting to a warming climate was now "a matter of life and death" and without action, thousands of Britons would die each year, reports Sarah Knapton.

The committee said rules brought in to make modern homes and offices more energy efficient had left householders and workers to swelter in overly insulated buildings with little ventilation. It called for updated guidelines.

The MPs' report also said that road and rail services had not been built to cope with such hot weather, with just half of Britain's motorways surfaced with material that can withstand high temperatures and rail tracks increasingly at risk of buckling.

A commuter feels the heat on London Bridge on what is predicted to be the hottest day of the year Credit: Tom Nicholson/LNP

The Royal College of Nursing (RCN) warned that people were "vomiting and passing out" from the heat and MPs said health guidance should be issued to employers and schools to relax dress and uniform codes and allow flexible working.

A survey carried out by the committee also found schools were so hot in summer that nine in 10 teachers are forced to pay for fans to make classrooms bearable.

MPs warned that by the 2040s, Britain would face similar heatwaves every two years, and called for a minister to be appointed to tackle the growing crisis.

At a glance | Heat warning levels

Toxic air prompts air pollution warnings

A mix of toxic air, extreme highs, emissions from the continent and a lack of cloud cover have caused a "high" air pollution alert to be issued for London.

Air quality alerts will be displayed at bus stops, river piers, on busy roads and at the entrances to London Underground stations on Thursday.

Mayor Sadiq Khan said: "This is the second time in six months that we have had to use the 'high' alert system and shows just why air pollution is a public health crisis."

Children, the elderly and people with lung or heart problems have been advised to reduce strenuous exercise and physical exertion.

High pollution is forecast today - we recommend that Londoners take caution when outdoors, especially if suffering from lung and heart problems. Sign up for alerts here: https://t.co/kz8kqOSeYopic.twitter.com/N0xLdnep6Q — Mayor of London (@MayorofLondon) July 26, 2018

Blood supplies drop as donors too dehydrated

Health Secretary Matt Hancock has been urged to set out what measures he is taking to make sure the NHS can cope with the heatwave.

Shadow health secretary Jon Ashworth said hospitals are facing year-round pressures, saying "the traditional lull in NHS activity during the quieter summer months is a thing of the past".

Blood supplies have dropped, health officials have said, saying some people have been too dehydrated to donate while others have chosen to stay in the sun.

Heatwave | Read more

Storms could bring flash floods and power cuts

Thunderstorm warnings are in place for parts of northern and eastern England and the Midlands for Friday, with people warned of flash flooding, lightning strikes, hail or strong winds.

This could lead to flooding of homes and businesses, difficult driving conditions and potential power cuts, the Met Office warned.

Chief meteorologist Paul Gundersen said: "The heatwave conditions will continue across much of England, with temperatures into the mid to high-30s Celsius in many places from the Midlands eastwards on Thursday and Friday and it's possible that we could break the all-time UK record of 38.5C if conditions all come together."

Mr Gundersen added: "There is the chance of thunderstorms breaking out over some eastern parts of England on Thursday, but it is Friday when we see intense thunderstorms affecting many central and eastern areas.

"Whilst many places will remain dry and hot, the thunderstorms on Friday could lead to torrential downpours in places with as much as 30mm of rainfall in an hour and 60mm in three hours.

"Large hail and strong, gusty winds are also likely and combined could lead to difficult driving conditions as a result of spray and sudden flooding."

Britain swelters in heatwave, in pictures

University of Sussex graduates cool off on Brighton beach after their graduation ceremonies Credit: David McHugh/Brighton Pictures

Holidaymakers and daytrippers pack the beach at Lyme Regis in Dorset Credit: Celia McMahon/Alamy Live News

A woman tries to cool down in Cambridge as a passenger on a punt Credit: Martin Dalton/REX/Shutterstock

Three-year-old twins Corin and Elliott Brennan from Leith have fun in the sun playing frisbee Credit: Dave Johnston

A man walks past a reproduction of a section of the Royal Naval college ceiling by British artist James Thornhill Credit: Leon Neal /Getty

A Queen's Life Guard swelters in the heat at Horse Guards Parade on Whitehall Credit: Jeff Moore

Heatwave picture call out

Harvest starts early and reservoirs running dry

Farming leaders have warned that crops are being hit and livestock are having to be fed with feed that should be held for winter as grasslands are parched.

The dry spell has been most prolonged in East Anglia and south-east England where the last day of very widespread rainfall was seen on May 29.

Dry earth cracks in a farmer's field near Altringham, Cheshire Credit: PHIL NOBLE /Reuters

Firefighters have urged the public to avoid "careless and reckless" behaviour during the ongoing heatwave as crews across the country deal with a high number of field fires.

And pet owners have been urged to avoid exercising their dogs and other animals in the hottest parts of the day due to the risk of burnt paws on scorching pavements, as well as the chance of heatstroke.

Video: How to keep gardens looking healthy in the heat

Britain's driest half of summer on record

The heatwave baking Britain comes as extreme hot weather grips northern Europe.

The UK has seen the driest half of summer on record, with just 47mm (1.85 inches) of rain between June 1 and July 16.

The Met Office said several places have had 54 consecutive dry days, starting on May 30, including a few which have had less than 1mm (0.04in) of rain in the entire 54-day period - the longest spell since 1969, when 70 days passed with no significant rainfall.

The dry spell has lasted longest in E Anglia and SE England. Brooms Barn, Bury St Edmunds, has had no rainfall since 5 June, 48 days ago. We actually classify a 'dry day' as less than 1.0mm of rain - several sites have had 54 consecutive 'dry days' https://t.co/5NYY91P8FNpic.twitter.com/RzaFngGBt8 — Met Office (@metoffice) July 24, 2018

The longest run of days with no rain at all this summer so far is 48 days at Brooms Barn, near Bury St Edmunds, since June 5.

Conditions this week have been nearer normal for the time of year in Northern Ireland and western Scotland, which are seeing lower temperatures and rainy spells.

How much water helps to avoid dehydration?

A leading surgeon has recommended people drink three litres of water a day and said a "radical culture change" towards drinking water is required to help the country stay hydrated during the heatwave.

Bhaskar Somani, a consultant urological surgeon at University Hospital Southampton NHS Foundation Trust, said attitudes towards water consumption "remained poor" even among those at higher risk of health problems.

He said: "We should take this opportunity to remind people that consumption of three litres of water a day is a small price to pay to help maintain and improve your health, particularly during heatwave spells such as the one we are in right now."

How to cope in hot weather

He spoke out following a study of 162 patients who received treatment for kidney stones - for which poor hydration is a significant risk factor - at Southampton General Hospital.

It found less than a third (28 per cent) increased their water intake, despite receiving advice after treatment on the need to drink 2.5 to 3 litres a day, particularly in the summer months, with the average intake of water at around 1.5 litres.

Almost a quarter (22 per cent) said the reason for avoiding water was because they did not like the taste, while 26 per cent blamed their habits and 10 per cent said they only drank when thirsty.

Why is it so hot? Your questions answered

What has triggered this heat?

In the short term, the current weather phenomenon can be attributed largely to the position and the strength of jet streams - fast moving air typically five to seven miles above the Earth's surface. Such jet streams are crucial to bringing in new weather systems.

What does that mean?

Becky Mitchell, meteorologist at the Met Office in Exeter, said: "The jet streams are not very strong to the north of the UK. When the jet stream is like that, it means we're under a period of high pressure, currently drawing up hot and humid air from France."

What causes a low jet stream?

Sometimes it is just a feature of the weather at the time. However, this prolonged period of dry and very warm weather will inevitably cause scientists to look at the long-term impact global warming is having on the planet.

What would ordinarily be happening across the UK at this time of year?

Again, when the jet stream is further south it means cooler weather systems are able to come in from the Atlantic. That is not happening at the moment, hence the extended period of hot temperatures.

Will we have much more of this?

In short, yes. It is probably fair to say that things will get worse (that is to say, hotter) before they get better. And it's all building towards Friday being the hottest day of the year, with temperatures expected to hit 36C (96.8F) in the south east before dropping back to the high 20s again. Interestingly, despite the driest start to summer since 1961, the previous three years have each had a top temperature exceeding 33.3C (91.9F), the record high for 2018 so far.

Any chance of rain?

Succour is on its way. Thunderstorms are expected in parts of eastern and northern England on Friday, according to the Met Office, with a chance of hail and strong winds alongside the torrential downpours.

But will it actually make any difference?

The volume and persistence of the rainfall will have a variable impact on the overall temperature. Extended periods of very hot and dry weather mean the ground has itself been heated - a light shower is going to do little to change that. Nor is it likely to fill the reservoirs, which are in desperate need of a top-up. But many gardeners and farmers are crying out for rain. Any cooling of the temperatures will be particularly welcomed by dog walkers, who have been forced to take their pets out very early in the morning or late at night when the temperatures have dropped to something less punishing.

Weather map for Thursday and week ahead

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