The Met Office has provisionally confirmed today is the hottest day on record as temperatures pass 40C.

Thermometers hit highs of 35C in the county yesterday, but the forecast suggests Kent will reach 39C by 5pm.

A temperature of 40.2C was recorded in Heathrow and later a new provisional UK record temperature was been recorded as 40.3C at Coningsby, in Lincolnshire, the Met Office said.

A red weather warning is in place in parts of Kent – including Dartford and Chatham – as experts warn the heat will lead "to widespread impacts on people and infrastructure".

Speaking to Parliament yesterday, Health Secretary Steve Barclay described Tuesday afternoon as "the point of maximum concern".

“We’re seeing an increase in calls to emergency services, and the extra resource we have put in place is to manage that," the senior Tory said following a meeting of the Cobra emergency committee.

“But there’s also a time lag in the data because the highest point of the expected heatwave is actually going to be tomorrow (Tuesday) afternoon, so that’s the point of maximum concern.

"That’s why we put more call handlers in place.

"It’s why we put additional funding in – an extra £150 million for the ambulance service, a further £50 million for 111, and indeed other support such as £30 million for auxiliary ambulances. So extra resource has been put in place."

Dartford, Canterbury, Sittingbourne, Faversham and Tonbridge are all set to see peaks of 38C this afternoon.

Meanwhile, residents in Sevenoaks, Chatham and Ashford will swelter in 37C heat.

This comes after a row between school bosses erupted over whether to keep children in hot classrooms this week.

Rainham Mark Grammar will today hold lessons online, with teachers insisting "we are taking the health and safety of our school community seriously".

But Steve Chalke, who runs academies on the Isle of Sheppey and in Medway, branded such a decision "unbelievably irresponsible".

"The decision to shut a school at any time has huge ramifications, economically and socially," he explained.

"Shutting them would be unbelievably irresponsible.

"School will be cooler because we can manage it and our parents have to work."

The current UK temperature record is expected to fall on Tuesday, with temperatures set to reach a “crazy” 41C in Yorkshire and Lincolnshire, and hit 40C in London.

Met Office meteorologist Luke Miall said: “I’ve been a qualified meteorologist for 10 years, and telling people about 41C in the UK doesn’t seem real.

“It’s crazy how we are talking about these sorts of values, I’ve never seen the models coming up with these values.

“It’s been quite an eye-opener to climate change with all these temperatures in the UK.”

Climate change, which has pushed up global temperatures by 1.2C on pre-industrial levels, is making hot spells longer, more intense and more likely.

Experts have warned of the need to adapt homes, cities and infrastructure in the UK for further heatwaves in the future.