Why do heatwaves in the UK feel hotter than abroad?

While the heat can be welcome when you’re on holiday, it can feel unbearable at home

People sitting in the sun by Tower Bridge in London in September 2021
(Image credit: SOPA Images/Getty Images)

For the first time ever the Met Office has issued a “Red Extreme” heat warning, with areas of the UK forecast to reach 40C next week.

The red alert means that there is a “very likely” risk to life and it will cover “an area from London up to Manchester and then up to the Vale of York”, reported The Telegraph.

There is also a 50% chance that temperatures will reach 40C “somewhere in the UK, likely along the A1 corridor”, which would be an “iconic threshold” that “shows that climate change is with us now”, said Met Office spokesperson Grahame Madge.

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And there is an 80% chance that the mercury will exceed the 38.7C record set at Cambridge Botanic Garden on 25 July 2019.

“Substantial disruption” is predicted and Brits are advised to make changes to their daily routine, such as avoiding travel during the hottest times of day.

‘Britain feels a lot hotter’

As the UK prepares for soaring temperatures, many people have questioned why British heat feels more “unbearable” than elsewhere, said Lucy Williamson on My London.

Her thoughts were echoed by a Twitter user, who wrote: “No idea why but when it is even only 25C in Britain feels a lot hotter than it does at well above 35C elsewhere.”

Humidity is one reason, explained the Met Office. The UK has a higher level of humidity than the European continent and “it is harder for the human body to keep cool as your sweat doesn’t evaporate as quickly.”

It also doesn’t help that buildings in the UK are “designed to keep heat in, compared to hotter countries”, which also makes “tropical nights” – defined as being where the temperature doesn’t drop below 20C – worse. No respite from the heat at night means our bodies don’t get a chance to cool down.

Partly, though, it is psychological. “When we are on holiday, we are expecting the heat and so come more prepared,” added the Met Office. When abroad on holiday our intentions are generally to relax and we’re more likely to drink water, go swimming, apply sunscreen, wear lightweight clothes and take regular breaks from the sun.

Back in the UK, as we carry on our daily lives, we are less likely to take as much care in warmer temperatures. As Williamson puts it: “Brits are notoriously bad at coping with the heat.”

Staying safe in the sun

Along with the red weather warning, the UK Health Security Agency has raised its heat health warning to level 4, which is issued when a heatwave is so severe that illness may occur among fit and healthy people.

It is important, then, to stay out of the sun between 11am and 3pm, “when the UV rays are strongest” and while both alerts are in place, the Met Office recommended.

Suncream is a must, as is carrying water with you when outside. Walking in the shade is also strongly advised, along with wearing a wide-brimmed hat.

And there are steps you can take to protect yourself from high temperatures while at home. Closing sun-facing curtains will “keep indoor spaces cooler”, although it is important to remember that at times “it may be cooler outdoors than indoors”.

The Met Office has also advised Brits to keep up to date with the latest weather forecast and warnings over the next few days.

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