Meteorologists fear the nation will have to “completely change its way of life” to have any chance of coping.
Last week’s sizzling heatwave saw one of the hottest days ever recorded as the mercury soared to 38C.
And climate change means summer temperatures are only going to get hotter, according to the Weather Channel.
Forecaster Leon Brown said: “I predict it is going to get even hotter and next year or a few years down the line the 40C will be smashed.
“In the future we will see the temperatures rising and rising and for longer periods of time as well.
“British people are not used to it and find it very difficult to cope with this extreme heat but we will have to account for the fact that it will become more frequent.
“These are unprecedented events but not for much longer.
“The temperatures we have been seeing in France are more akin to those you see in Saharan Africa and Britain is not too far behind.”
Sweltering conditions forced Brits to endure sleepless nights and uncomfortable days at work as temperatures peaked on Thursday.
The extreme weather also saw infrastructure descend into chaos as flights were grounded and scores of trains cancelled.
According to expert health advice, the likelihood of suffering from heatstroke rises dramatically when temperatures soar past 40C.
It would become life-threatening for vulnerable groups such as the elderly, young children and the ill.
Mr Brown also warned Brits to beware of dehydration in future punishing heatwaves.
He added: “Dehydration will become a real issue and is one of the many things the country needs to adapt to.
“We may have to change working patterns and make it compulsory for workers to take siestas during the middle of the day in these hot spells.”
Meanwhile, the Met Office faces the embarrassment of having to scrap Britain’s hottest ever day last Thursday.
Cambridge University Botanic Garden’s weather station – which recorded the 38.7C mark – is situated next to bare soil, which acts like a heater and has been branded a “sun trap”.
If 38.7C is wiped from the records, Britain’s hottest temperature since records began in 1841 will remain 38.5C on August 10, 2003, in Faversham, Kent.