Air pollution is spiking across Britain, France, and southern Europe amid record-breaking temperatures and scorching wildfires.
Catch up on the latest updates from overnight.
Key events
Live updates
By Bridget Judd
Stay up-to-date with the latest weather news
As much of Europe turns in for what is expected to be a cooler day on Wednesday (local time), this is where we'll leave things for today.
Thanks for following along — don't forget you can stay-up-to date with the latest heatwave news:
By Bridget Judd
The head of the UK's Meteorological Office reflects on hitting 40°C for the first time
Professor Stephen Belcher is the chief of science and technology with the Met Office, the UK's national weather service.
He says he "wasn't expecting to see this" in his career.
"In some ways, of course, 40 degrees is an arbitrary figure because we see the impact of heatwaves at lower temperatures, but for me it’s a real reminder that the climate has changed and it will continue to change.
"Research conducted here at the Met Office has demonstrated that it’s virtually impossible for the UK to experience 40 degrees C in an undisrupted climate. But climate change driven by greenhouse gases has made these extreme temperatures possible and we’re actually seeing that possibility now.
"If we continue under a high emission scenario, we could see temperatures like this every three years. We’re already committed to a level of warming and these extremes will get more extreme in the future.
"The only way that we can stabilise the climate is by achieving net-zero, and of course the UK has made some great strides in that direction already. But we want to stabilise the climate at a safe level and that means reaching net-zero soon."
By Bridget Judd
Some of these cities just aren't built for heat
We use to get 40 c at Raymond terrace in new south Wales .
- Alan moret
Morning, Alan.
While Australians might be used to seeing the mercury climb this high at the peak of summer, the usual July average maximum in London, for example, is about 23C.
As the ABC's Europe correspondent Isabella Higgins points out, Britain — with its centuries-old buildings and densely populated towns — faces real challenges during heatwaves.
"Few residential buildings are fitted with air-conditioning, a problem many schools, aged-care homes and even some hospitals have struggled with in recent days.
"Most structures are designed to keep out wind and trap heat to overcome the long, cold winters.
Many British cities turn into "urban heat islands" when the temperatures soar, Professor Prashant Kumar, from the Global Centre for Clean Air Research at the University of Surrey, told the ABC.
"This happens wherever you have a lot of buildings which are made of concrete and other construction materials, like brick," he said.
"Also, on the roads which are made with asphalt … you can think of all of it as a kind of radiator. They actually trap the heat during the daytime and then this heat is released over time, making it even hotter."
By Bridget Judd
It's midnight in London, but fires continue to burn
By Bridget Judd
Americans endure 'dragon's breath' heatwave, set to last into next week
It's not just Europe experiencing record temperatures.
Across the United States, Americans have been enduring in some cases dangerously high heat that meteorologists say will last into next week.
More than 100 million people are living under excessive warnings or heat advisories this week, according to the National Weather Service.
In Oklahoma City, where a high of 43 Celsius was predicted on Tuesday, Colin Newman, 40, said it hits like "dragon's breath" when he steps outside, even in the early hours.
"We plan our days around getting from one air-conditioned place to another," he said.
The excessive heat in the United States comes hot on the heels of the European heatwave, but unlike in Europe, many American homes have air conditioning.
By Bridget Judd
It's not just humans trying to beat the heat...
Bioparco di Roma, a zoo in Rome, hasn't been immune to the heatwave that is also gripping France, Germany and Spain.
To help their cuddly companions beat the heat, they decided to hand out blocks of frozen fruit.
By Bridget Judd
UK experiences hottest day — and night — on record
The UK weather bureau says the country could experience temperatures like this every three years.
The ABC's Europe correspondent Steve Cannane says records were also set for the hottest night.
"Millions of [people] are really struggling to sleep at night in homes that are simply not built for these conditions.
"Also the infrastructure is struggling — the roads, the rail. All of the trains out of Kings Cross Station, they stopped them for a while because the rail had buckled and they simply could not run the trains."
By Bridget Judd
Hospital, homes evacuated in Greece as wildfire burns near Athens
Hundreds of people have been evacuated from their homes overnight as a wildfire threatens mountainside suburbs north-east of Athens.
Firefighters battled through the night, struggling to contain the blaze which was being intensified by strong gusts of wind.
The Fire Service said 15 planes and nine helicopters were involved in the firefighting effort on the slopes of Mount Penteli, 25 kilometres north-east of Athens before being grounded at nightfall.
Local officials said homes had been burned or damaged but there were no reports of injuries or stranded people. A children’s hospital in the area was also evacuated, officials said.
Greece has been spared the heat wave conditions currently plaguing countries in western Europe, but fire officials say that hot and dry conditions persisting for weeks as well as longer term temperature rises have increased the overall risk of forest fires.
More than 1,300 square kilometers (500 square miles) of land was damaged by wildfires in Greece last year, the worst damage recorded since 2007.
Fire Service spokesman Yiannis Artopios said four separate evacuation orders had been issued Tuesday, with push alerts sent to mobile phones in the affected areas.
“Its’s been a tough day,” the spokesman said, adding that more than 400 firefighters had been deployed.
By Bridget Judd
Here's what UK residents are going to wake up to
After a record breaking day, temperatures will return to near normal values from the west on Wednesday (local time).
It's not quite as good news for those in the south and east, however, with the Met Office warning it'll still feel "very warm and locally hot".
By Bridget Judd
'Britain is melting': How the UK is covering the heatwave
From a "wake-up call" to the "hottest in history", here's how the UK's major media outlets are covering the heatwave.
By Bridget Judd
A look at those fires across Britain
As we heard a short time ago, London's firefighting authority has declared a major incident in the British capital in response to the surge in fires.
One of them engulfed homes in the village of Wennington, with flames tearing across about 40 hectares of neighbouring tinder-dry fields.
By Bridget Judd
In pictures: how Europe is trying to beat the heat
With temperatures exceeding records across the continent, people are finding creative ways to stay cool.
Over in the UK, children flocked to the River Ver, while others tried to beat the heat with a barbeque.
In Germany, people took to the Dreisam river in Freiburg im Breisgau.
There were similar scenes in Berlin, with residents flocking to the Neptune Fountain in the city's downtown.
By Bridget Judd
How long could Europe's heatwave last?
There's some good news and bad news.
The World Meteorological Organization believes Europe's heatwave may have already peaked, but temperatures may remain above normal into the middle of next week.
"The question that everybody is asking looking ahead is - when is this going to end?" said Robert Stefanski, chief of Applied Climate Services at the WMO.
"Unfortunately, looking at all the models from all our partners at a national and regional level, possibly not until middle of next week."
At the same briefing, WMO Secretary-General Petteri Taalas warned that he expected to see a "much higher" number of heat waves in future due to climate change.
"The direction is clear and in the future these kind of heat waves are going to be normal and we will see even stronger extremes."
By Bridget Judd
Footage shows extent of wildfires burning across Europe
Firefighters in Spain, France, Greece and Portugal are battling blazes fuelled by high temperatures.
By Bridget Judd
Heatwave leads to more than 1,000 deaths in Portugal
Portugal has reported more than 1,000 deaths due to the current heatwave, with the nation's health chief warning that the country must gear up to cope with rising temperatures.
"Portugal ... is among one of the areas of the globe that could be (more) affected by extreme heat," Graça Freitas, head of health authority DGS, told Reuters.
"We have to be more and more prepared for periods of high temperatures."
Temperatures across drought-stricken Portugal surpassed 40C last week. Although they have dropped in the last few days, Ms Freitas said they remained above normal levels for this time of the year.
DGS previously reported 238 excess deaths due to the heat wave from July 7 to 13, but Ms Freitas said the number of fatalities has now increased to 1,063 for the period up to July 18.
By Bridget Judd
Here are the highest temperatures from across the UK
At least 34 sites have exceeded the UK's previous national record of 38.7C
According to the Met Office, they include:
- Coningsby: 40.3
- St James's Park: 40.2
- Heathrow: 40.2
- Gringley On The Hill: 40.1
- Kew Gardens: 40.1
- Northolt: 40.0
By Bridget Judd
London declares 'major incident' as fires surge
London's firefighting authority has declared a major incident in the British capital in response to the surge in fires amid the record-breaking heatwave.
The London Fire Brigade said it had deployed dozens of fire engines to several fires in and around the city, including thirty to a grass fire in east London.
"Firefighters are still meeting the needs of our communities, but declaring a major incident allows us to focus our resources," the brigade said.
Britain recorded its highest ever temperature, breaking 40C for the first time, as a heatwave gripping Europe intensified, scorching fields and damaging airport runways and train tracks.
"This is critical: @LondonFire is under immense pressure. Please be safe," London Mayor Sadiq Khan said on Twitter.
By Bridget Judd
Temperatures exceed 30C even at 3:00am
Good morning.
Air pollution is spiking across Britain, France, and southern Europe amid record-breaking temperatures and scorching wildfires.
Scientists with the EU Copernicus Atmosphere Monitoring Service have warned of unhealthy levels of ozone pollution across southern and western Europe which could soon affect north-western regions.
It comes as hot night time temperatures are hindering firefighting responses across Europe and worsening health conditions as bedtime fails to provide a cooling reprieve, experts say.
On Monday, Britain experienced its warmest night on record with temperatures failing to dip below 25C in some places.
Meanwhile, La Hague in Normandy, France, registered 32.8C at 3:00am on Tuesday.
