The Met Office has issued a red warning for extreme heat, with temperatures expected to reach at least 37°C in London on Wednesday and remain above 35°C across most of the 148 affected areas on Wednesday and Thursday. In such conditions, the UK government advises against using electric fans, as they become ineffective above 35°C and can actually increase the risk of dehydration.
Why Fans Are Counterproductive in a Heatwave
According to the UK Health Security Agency (UKHSA), electric fans only work when the air temperature is below 35°C. Above that threshold, fans merely circulate hot air, providing a false sense of coolness without actually lowering the room temperature. The government's heatwave guidance states: "Use electric fans if the air temperature is below 35°C, but do not aim the fan directly at your body as this can lead to dehydration."
Fans do not cool the room; they only move air around. While they may provide temporary relief, they can lull people into neglecting more effective cooling measures such as staying hydrated, taking cold showers, and shading windows.
Official Recommendations for Keeping Cool
The UKHSA advises closing curtains, increasing airflow through open windows (but only when temperatures drop), and avoiding direct sunlight. Regular water intake and cold showers are also recommended. These measures are crucial as climate change drives more frequent and intense heatwaves. The government notes that all of the warmest years on record in the UK have occurred since 2002, and in July 2022, temperatures exceeded 40°C for the first time.
Heat-related deaths are a growing concern. In 2022, an estimated 2,803 people aged 65 and over died due to heat in England. The UKHSA projects that heat-related deaths could triple by 2050. Hot weather increases the risk of heart attacks, strokes, lung problems, and other diseases, particularly among older adults, babies, young children, and people with underlying medical conditions.
Red Warning and Temperature Forecast
The Met Office's red warning for extreme heat runs from midnight on Wednesday until 9pm on Thursday. However, temperatures in London may still reach 36°C on Friday. The UKHSA works with the Met Office to issue health alerts during such periods, aiming to prevent heat-related harm through simple actions.
Despite the temptation to use fans, the official advice is clear: they are not only ineffective but potentially harmful in extreme heat. The best strategies are to keep the home cool, stay hydrated, and limit exposure to the sun.
