As the UK swelters under yet another relentless heatwave, many residents are left pondering why these scorching days feel particularly unbearable compared to those experienced in other parts of the world.
Despite sharing the same blazing sun and rising global temperatures, the heat in the UK seems to hit differently, leaving many to wonder if there’s more to it than just degrees on a thermometer.
Still, most of the world sees the British heat, topping out around the 30°C mark, as almost quaint – especially in the face of climate change-induced wildfires ravaging much of the US and Europe. But there's more to the story.
Before dismissing it as typical British moaning, heed our warning: according to science, it is far worse when you get here.
“A heatwave is in many ways a subjective event. Different countries define a heatwave in different ways because it means something different depending on the average conditions that people are expecting,” climate expert Prof Hannah Cloke tells BBC Science Focus.
“32°C is much hotter than normal for July in England, but pretty common in, say, New York. And it isn't just about maximum daytime temperature, which is often the figure people look at when they are looking at heat.”
There’s something in the air
One thing you may have noticed about the UK is that it’s an island, which means, obviously, it’s surrounded by water.
You’d be forgiven for thinking that having all that nice, cool water about might cool things down somehow. In fact, the opposite is true.
“The UK climate is relatively humid compared to many other European countries because of the UK's proximity to the ocean and the prevailing south-westerly winds which bring moist sea air over land,” meteorologist Dr Matthew Patterson tells BBC Science Focus.
There are four main ways our bodies can lose heat: radiation, conduction, convection and evaporation.
The first three, Patterson explains, essentially rely on a temperature gradient between you and the air. If there air is cooler than you are, then you can lose heat to it.
“This process becomes less effective as the air gets warmer and so you start to sweat,” Patterson says. Enter evaporation.
“Sweating cools you down because when the water evaporates it transfers energy away from your body. However, sweating is less effective if there is already a lot of moisture in the air,” he says.
Wind speed also has a role to play in evaporation, since more wind can whip moisture away from your skin with relative ease.
As Cloke puts it: “Forecasters and health agencies measure and forecast the effects of temperature, humidity and windspeed on the human body in terms of a ‘feels like’ temperature, or with indicators such as the Universal Thermal Climate Index (UTCI).
“Two regions might have identical temperatures, but one might feel OK, while the other leaves people dangerously overheated. Measures like the UTCI can provide planners with a much better understanding of where and when the impacts of a heatwave will be felt.”
British houses aren’t fit for purpose
Another reason – possibly the biggest – we Brits aren’t cut out for the heat is the design of the place. Anyone who’s been on the London Underground in the summer can attest to some serious design flaws when it comes to managing the heat.
“Most homes in the UK don't have air conditioning as standard, and for good reason, because for most of the year, it would be pointless,” Cloke says.
Granted, air conditioning is fairly useless for much of the year. But the properties themselves also pose a problem.
According to UK government data, in 2022, one in six homes in England and a fifth of homes in Wales were built before 1900. Meanwhile, only 7 and 5 per cent, respectively, were built post-2012.
This means UK homes are usually designed without things like climate change and heat waves in mind.
“They’re built to let sunlight in, which can lead to a substantial build-up of heat during the day,” Patterson says. Instead, houses in Europe and the US often have external shutters, which do a great job of keeping the heat out.
This cultural hangover from the cold days of old is something that will have to change as temperatures continue to creep up in the UK over the coming decades. Four of the five hottest days on record in the UK have occurred since 2020, with the mercury topping out above 40°C for the first time in 2022.
“Part of the problem comes from a lack of understanding of what to do to keep our homes cool. People often don't know what to do in the heat,” Cloke says.
“As a society, many of us are not ready for higher temperatures as it is, and we are only going to see more and more hot days and nights, and longer, more intense hot weather spells in the UK, as a result of climate change in the future. But we do like to moan about the weather, don't we?”
About our experts
Hannah Cloke OBE is a British hydrologist who is a professor of hydrology at the University of Reading. She was awarded the European Geosciences Union Plinius Medal in 2018 and appointed Officer of the Order of the British Empire in the 2019 Birthday Honours. She is interested in flood forecasting and risk management and works with the Met Office, Environmental Agency and the European Centre for Medium-Range Weather Forecasts (ECMWF).
Matt Patterson is a postdoctoral research assistant at the University of Reading. His primary interests are in atmospheric dynamics, the prediction of seasonal to decadal timescales and climate change. Previously, he studied the role that global warming trends have on seasonal prediction models for Europe.
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