Britain could bake under record-breaking heat as temperatures could potentially climb to 39C on Thursday.
The scorching conditions may spark thunderstorms, which could trigger travel delays, flash flooding, and power cuts.
The dangers of cooling off in lakes, rivers and the sea were highlighted by emergency services after the bodies of three people were pulled from the water on Wednesday after they reportedly got into difficulty swimming.
A yellow weather warning is in force for most of England, except the south-west, and parts of Scotland from 3pm on Thursday until 4am on Friday.
According to the Met Office, there is a 60% chance the temperature could rise above the current all-time UK temperature record of 38.5C on Thursday.
“It will get into the 30s across the country and reach the mid-30s in the south-east,” Met Office meteorologist Greg Dewhurst said.
“If it is to get to 39C, it will happen somewhere between London and Cambridge.
“Temperatures locally could also break July or all-time records.”
Lightning storms have already caused fires and rail disruption this week during the heatwave. Network Rail warned that speed restrictions might be introduced in areas where tracks were at risk of buckling.
Extreme weather action teams (Ewats) had been activated to keep passengers safe and trains running, it said.
The Rail Delivery Group, which represents the industry, advised passengers in London and the south-east to consider changing their travel plans on Thursday.
London North Eastern Railway (LNER), which runs inter-city services on the East coast mainline, is advising customers against travelling on Thursday.
It said some services were likely to be cancelled or delayed as speed restrictions would be imposed between Peterborough and London King’s Cross.
The Met Office has warned that heatwaves are on the increase as a result of climate change.
The scorching temperatures gripping the UK and much of Europe come against a backdrop of global warming of 1C since the industrial revolution driven by greenhouse gas emissions.
Both Belgium and the Netherlands broke their all-time maximum temperature records on Wednesday, reaching 39.9C and 39.1C respectively, the Met Office said.
Higher temperatures are making extreme hot spells more likely and more intense, experts warn.
UK weather: nation braces for record-breaking heat – The Guardian