Having record-breaking summers will become a certainty due to climate change, experts have warned, as the UK begins to swelter in what could be the hottest day of the year so far.

Just a week after Britain recorded the third warmest day on record on July 31, with 37.8C (100.04F) recorded in Heathrow, Friday could see temperatures rise to – and possibly surpassing – 37C (98.6F) in London and the South East.

Michael Byrne, lecturer in earth and environmental sciences at the University of St Andrews, warned that two near-record temperatures so closely spaced is “unusual”.

“But it’s not surprising given climate change is happening and accelerating,” he told the PA news agency.

“Breaking temperature records year-on-year will absolutely keep happening, unless we take drastic action against climate change that’s a certainty.”

The Met Office revealed in its latest report covering the climate of the UK, published on July 31, that the most recent decade has been on average 0.9C warmer than the period between 1961-1990, with 2019 being 1.1C above the 1961-1990 average.

It found that the earth’s surface temperature has risen by 1C since the pre-industrial period between 1850-1900.

Mr Byrne said that while 1C may not sound dramatic, there is a huge amount of variation region-to-region.

“The land region has warmed substantially higher than 1C,” he said.

“We think in 50-100 years we’ll see 2-3C of surface warming, with more over land and over the Arctic, which will present huge challenges and implications for people’s health.

“Parts of the Middle East won’t be habitable, which I find quite terrifying.”

According to the Met Office, all of the UK’s 10 warmest years have occurred since 2002, with last year seeing the hottest day on record at 38.7C in Cambridge Botanic Garden on July 25.

Mr Byrne cited the 2003 heatwave which has been linked to nearly 15,000 deaths, most among the elderly, in France and which caused 2,000 excess deaths in the UK.

“For quite a long time we saw climate change coming, but it seemed an abstract concept,” Mr Bryne said.

“The last five years has hit home for me that it’s happening now, it can’t be ignored anymore.”

Ilan Kelman, professor of disasters and health at University College London, warned the UK’s rising temperatures will make it “highly dangerous” for people to be outside if more isn’t done to curtail climate change.

He said: “These temperatures are unfortunately in line with the expectations for heat under climate change, which is one of the most concerning health impacts.

“Without stopping human-caused climate change, these levels of summer heat and humidity will become regular, making it highly dangerous for us to be outdoors and even indoors without continual cooling.

“Air pollution can also worsen under heat with its knock-on health effects, such as for cancer and asthma.”