As an intense heatwave grips large parts of Western Europe, Britain has been sweltering under temperatures of around 35°C — levels that have forced schools to shut, strained power supplies and prompted health warnings. Yet, for many Indians, those temperatures may not sound particularly extreme. After all, cities across north and central India routinely experience summer highs of 45°C or even higher.
So why does a 35°C day in Britain often feel more oppressive than a 45°C afternoon in India?
The reality is that the human body doesn’t respond to air temperature alone. Humidity, overnight temperatures, building design, urban infrastructure and even how accustomed people are to heat all influence how hot a day actually feels.Think, the ‘feels like’ tab when you check the weather on your phone.
Humidity Makes The Difference
One of the biggest reasons is humidity. Britain is surrounded by the Atlantic Ocean and several seas, making its air far more moisture-laden than many hot regions.
The human body cools itself by sweating. But sweat only works if it evaporates. In humid weather, evaporation slows because the air is already saturated with moisture. As a result, the body struggles to release heat, increasing the risk of heat exhaustion, dehydration and heatstroke.
This is why meteorologists often rely on wet-bulb temperature, which combines air temperature and humidity, rather than the thermometer reading alone. A humid 35°C can place the body under similar physiological stress as much higher temperatures in drier climates.
Britain’s Homes Trap Heat
Unlike India, Britain’s homes were built to retain warmth during long, cold winters. Brick walls, insulated roofs and relatively poor cross-ventilation mean many homes absorb heat during the day and release it slowly overnight, effectively turning into “thermal batteries.” Air conditioning also remains uncommon in most British households.
By contrast, many Indian homes are designed with extreme summers in mind, using ceiling fans, natural ventilation, shaded courtyards and, increasingly, air conditioners to keep indoor temperatures manageable.
People Adapt To Heat Differently
Another major factor is acclimatisation. Across much of India, temperatures rise gradually through spring before peaking in May and June. That gives people time to adapt. Over repeated exposure, the body becomes more efficient at sweating, conserving salt and regulating temperature.
British heatwaves, however, often arrive suddenly after weeks of cool weather, leaving little time for physiological adaptation.
Daily routines also differ. In India, people commonly avoid outdoor activity during the hottest hours, while schools, workplaces and public services are more accustomed to functioning during extreme heat.
Warm Nights Make Recovery Harder
Britain’s long summer days allow buildings, roads and pavements to absorb heat for many extra hours. Even after sunset, urban areas continue releasing that stored heat.
When overnight temperatures remain above 20°C —known as “tropical nights” — the body gets little chance to cool down and recover from daytime heat exposure. Combined with the urban heat island effect, this can significantly increase health risks, particularly for older adults.
In countries like India, people, buildings and daily routines have evolved around recurring periods of extreme heat. Britain, on the other hand, is a country whose homes, infrastructure and public services were largely designed for a much cooler climate.
As climate change brings hotter and more frequent heatwaves to Europe, that mismatch is becoming increasingly visible.