Nats said in a statement: "We are doing all we can to fix it as soon as possible".
"Anyone due to fly in the morning is urged to check with their airline for the status of their flight before travelling to London Stansted Airport".
"Due to extreme weather conditions across Europe this evening, Heathrow and other airports are experiencing delays and cancellations to flights".
British Airways said it had been affected by severe weather conditions overnight as well as by the technical issue.
"Passengers should contact their airline for the latest information about their flight".
Lynn Morrison, a passenger at Heathrow Airport, took to social media to share an image of the crowded airport, describing the conditions as "chaos".
Heathrow also said that a number of flights had been delayed or cancelled but did not confirm how many planes had been grounded.
Un avocat lance une action collective contre Uber Eats
Les coursiers n'ont par ailleurs aucune information sur la destination finale de leur trajet et ce qu'il va leur rapporter. Contrairement à un vrai travailleur indépendant, ils ne sont pas en mesure de refuser une course.
Pictures posted on Twitter showed enormous queues of stranded passengers building up at Heathrow on Friday morning.
Alana Gomez, spokeswoman for travel comparison website Jet Cost, said: "Whilst passengers are justifiably aggrieved by the lengthy delays, they must understand that in these situations the safety of the passengers and crew is paramount, and the conditions felt yesterday made it unsafe to fly". Twitter/@lynn_morrison66Long queues could be seen around Heathrow airport as passengers waited for updates on their flights.
Donna Graham tweeted: 'There are hundreds of people queuing at Heathrow.
It comes after the Met Office yesterday issued weather warnings for large swathes of the country, stretching south-east across the midlands and as far north as Scotland.
"The thunderstorms could continue on and off through the course of the day", Met Office meteorologist Greg Dewhurst told PA.
Thursday was the hottest July day on record, with the 38.1C (100.6F) in Cambridge beating the previous record of 36.7C (98.1F) set in Heathrow four years ago.
New high-temperature records have also been set in parts of Belgium, Germany and Holland as a heatwave grips western and central Europe, pushing above 40C.
Sachez que, dès la rentrée, je serai là pour défendre ce dossier extrêmement important pour les Français et Françaises". Interrogée par Le Parisien vendredi, elle a aussi expliqué être arrivée "essoufflée" et paniquée pour cette interview.
For the first quarter of 2019, real GDP is estimated to have increased 3.1 percent (table 1), the same as previously published. Economists also noted that business capital investment fell in the April-June quarter for the first time in three years.
If this were to be the case then it would be a real shame for Arsenal as they had the deal all but officially sealed up. Zidane confirmed after the game it was because he was close to sealing a move away from the club.
Another surveillance video from a market about eight minutes away from Sardis Lake shows Kostial and Theesfeld together. Theesfeld's father, Daniel Theesfeld , a doctor in Texas, said in a statement to WMC that his son was innocent.
The company has not specified a release date for the Mac Pro beyond saying it will be available to order in the fall. Experts said there was little chance that Trump's tweets would have any impact on the company's investment in China.
Another surprise was added when the Raiders announced that Brown will start training camp on the non-football injury list. Antonio Brown showed up to training camp in a hot air balloon Friday but now he is on the non-football injury list.
In April, the rise of Candida auris ( C. auris ), a deadly antibiotic-resistant fungus, was brought into public attention. Arturo Casadevall , an author of the study shared, the fungal infections have not been very common in humans.
Of the three other rocks, Asteroid 2019 OD was the largest, believed to be between 170 feet and 393 feet across. Earth almost had a devastating collision with an asteroid travelling at almost 15 miles a second today.
Jay-Z will no longer be performing at the upcoming Woodstock 50 festival, a source with direct knowledge of the matter told CNN . The new location was designed for such events and could more efficiently adapt to organizers' needs.
In the coming days he'll speak on other aspects of a packed domestic agenda that looks suspiciously like an election platform. It's nearly certain that opposition lawmakers will try to topple Johnson's government in a vote of no-confidence in September.
And one individual who has this evening moved to make abundantly clear that he is Foden's biggest fan is Pep Guardiola . It's a challenge we're definitely up for. "Manchester is a lovely place, even though I live pretty much near Crewe".
Canadian police confirm sightings of murder suspects
Police are encouraging the public to reach out with any information they may have before sharing possible tips on social media. Many of Gillam's residents are hydroelectricity workers employed at one of the three large nearby generating stations.
Pompeo says he'd go to Iran if needed
The US State Department said it has no updates on the US-North Korean meetings. I would welcome the chance to speak directly to the Iranian people'.
Trump fumes over France's tech tax, threatens retaliation
Last week, Mr Trump spoke to Mr Macron as he about the country's proposed digital services tax, the White House said. Chinese, German, Spanish and British firms are also affected, as well as the French online advertising firm Criteo.
Watch freakish incident that got Rowe and Martin expelled
Rowe and Martin were both later thrown off the race as it emerged there had been a little more than simple jostling. Speaking on ITV4, Thomas said it was the job of such riders to get their team's star men into strong positions.
AIA extends Tottenham sponsorship until 2027
Spurs finally moved into a new 62,000 seater stadium, which British media said cost one billion pounds, towards the end of last season on the site of their old White Hart Lane ground and have invested in a state-of-the-art training centre.
Ozil, wife OK after attempted carjacking
His distinctive auto with its gold trim was seen left in the middle of Golders Green Road with the driver's door left open. Ozil , his wife and Kolasinac then fled inside a Turkish restaurant on Golders Green where they are regulars.