A map has shown that Britain was hotter than 99% of the world on Tuesday, as temperatures rose to a record 40C.
Meteorologist Ben Noll shared a map that outlined the extent of the heat in the UK over the past few days.
On Tuesday, a new record for the hottest day – 40.3C – was provisionally recorded in Coningsby, Lincolnshire.
The sweltering heat fuelled fires and widespread transport disruption.
The Met Office said 34 observation sites across England had provisionally broken the record, ranging from Bramham in West Yorkshire to Charlwood in Surrey, while a further five had equalled it.
A total of six sites, mostly in Greater London, saw temperatures reach or exceed 40C.
Scotland also experienced its hottest day on record, with the temperature reaching 34.8C in Charterhall in the Scottish Borders, Met Office provisional figures showed.
New Zealand meteorologist Noll tweeted a map that showed only a handful of places were hotter than the UK, including parts of France, the US, North Africa, the Middle East and Asia.
Noll wrote: "If you're shaded in blue on this map, then you're in the ~99% of Earth forecast to be cooler than the UK today."
Heatwaves are being made more intense, frequent and longer by climate change, and scientists said it would be "virtually impossible" for the UK to have experienced temperatures reaching 40C without human-driven global warming.
Watch: UK records 'highest-ever' temperature as heatwave scorches country
Professor Stephen Belcher, the Met Office’s chief scientist, warned temperatures would get more extreme in the future, and the only way to stabilise the climate was to cut greenhouse gas emissions to net zero.
Professor Tim Palmer, Royal Society research professor at University of Oxford, added: "What we as a global community cannot cope with is a deadly combination of high temperatures and high humidities where the human body cannot lose heat.
"That's the big story – the hell of Earth that may be awaiting us, caused by human-induced climate change.
"Heathrow's 40C-degree temperature is just a small sign of the path that we may now be on, to a world where these deadly events become commonplace in many parts of the subtropics and tropics.
"We in the UK will feel the effects of these deadly heatwaves only indirectly, from the inevitable tide of humanity migrating polewards trying to find some sort of relief."
It will be fresher for most places in the UK on Wednesday, although some parts of East Anglia will still see temperatures reach as high as 30C.
Wednesday’s rain, where it occurs, will be much heavier than on Tuesday, with a risk of localised surface water flooding, the Met Office said.