As temperatures soar across the UK, Hannah Fry's viral trick could help in minutes12:52, 27 May 2026With the UK sweltering in temperatures of 30°C, one place that tends to become significantly hotter is inside your car. Vehicles can reach dangerously high temperatures in direct sunlight - but a scientific expert has said there is a way to flush out the trapped hot air.‌Due to the 'greenhouse effect', sunlight is absorbed by the dashboard, seats, and carpet through your car windows. These interior surfaces then radiate this absorbed energy as trapped longwave heat, effectively turning the cabin into an oven.‌Mathematician and broadcaster Hannah Fry went viral online last summer with a scientific tip for cooling cars without air conditioning. However, she warned that Brits may look and feel a little silly when doing this in public.‌Rather than switching on the air conditioning, Hannah's advice is to wind down one of the windows on the nearside of the vehicle, then rapidly open and close the driver's door several times in quick succession. Harnessing the laws of thermodynamics, this can apparently bring the temperature down in "two or three goes".Speaking on her Instagram page, Hannah said: "The reason why it works is that when you open and close the door, especially if you do it quickly, the door, as it's moving outwards, sweeps out all of the air that's in its way, creating this area of low pressure that you get here. And, then that sets up something called 'bulk flow', which is where all of the hot, sweaty, horrible air inside the car is drawn outwards, and the only way to refill it is with nice fresh air from over on the other side."Content cannot be displayed without consent‌Air conditioning is standard in almost all new cars today. Knowing this tip can help if your air conditioning has failed, or you just need a quick way to flush out hot air before a journey.Fry, who was previously confirmed as a contestant for the second series of the BBC's Celebrity Traitors, claimed that her car felt "beautifully temperate" after trying this air-conditioning-free method of cooling down her car, reports the Express.Why is it turning warmer?The Met Office states that, while winds are anticipated to shift more southerly by the end of the week, the rise in temperatures is not due to warm air being carried directly from southern Europe or North Africa. Rather, the primary cause of the warming trend is the build-up of high pressure over and around the UK.‌As this high pressure intensifies, it forces air in the atmosphere to sink. This descending air is compressed as it descends, warming through a process known as adiabatic compression.Put simply, as air is compressed, its temperature rises. This process can substantially increase surface temperatures, even when the original air mass is not particularly warm. In this instance, much of the air sweeping across the UK still originates from the Atlantic, but warms up as it descends under high pressure. Temperatures are set to fall further this week, before a slight recovery on Saturday.‌With the recent spell of hot weather, people have been reminded of handy tips to keep cool. An electric fan is typically the first port of call when the mercury rises, but some Brits could be using theirs in entirely the wrong way.Experts at Which? suggest that people might actually feel greater benefit from their fans by pointing them away from their bodies. While it may seem completely counterintuitive, there's a reason why fans work best when directed towards an open window during the day.A team member said: "If it's cooler outside than inside, try pointing your fan out of an open window instead of directly at you. Fans don't cool the air, they move it, so this can help push hot air out of the room and draw cooler air in through other windows or gaps."Article continues belowOnce the outside temperature dips below that of your home, simply reverse the fan to face inwards. This draws the fresh, cool night air straight into your bedroom.