Researchers say sitting in a hot sauna could help people adjust to scorching summer temperatures, as the UK battles one of its hottest summers on record. Professor Jari Laukkanen, a cardiologist at the University of Eastern Finland, told the Daily Mail that repeated heat exposure can induce heat acclimation, meaning the body gradually becomes better at coping with heat.
Temperatures in the UK have exceeded 30°C on 31 days so far this year. Parts of the country have faced four separate heatwaves, and the UK Health Security Agency has issued amber and yellow heat health warnings for much of England.
How sauna bathing affects the body
Sauna bathing has surged in popularity in the UK in recent years, with enthusiasts making weekly or daily visits to one of the 844 saunas across the country. In a traditional sauna, bathers sit in temperatures between 70°C and 100°C (160 to 210°F) for 10 to 15 minutes before cooling off in ice-cold water.
Professor Laukkanen said this process can improve the body's thermoregulatory responses. He said adaptations can include earlier and more effective sweating, improved skin blood flow, expansion of plasma volume, and reduced cardiovascular strain during subsequent heat exposure, adding that together these changes may help people tolerate hot environments more efficiently.
Research also suggests that spending time in a sauna might improve how people behave in the heat, helping them get better at recognising signs of heat exhaustion and remembering to hydrate properly.
The UK's four heatwaves of 2026
- 25 to 30 May: highest temperature 35.1°C at Kew Gardens, London
- 23 to 27 June: highest temperature 38°C at Lingwood, Norfolk
- 6 to 15 July: highest temperature 35.7°C at Wisley, Surrey
- 28 to 30 July: forecast temperature of up to 35°C in eastern England
How to train the body for heat
According to Professor Laukkanen, heat training is best done slowly over a longer period. It typically takes about 40 to 60 minutes of heat exposure each day for four to six days, with benefits lasting around a week, though longer-term benefits are possible with extended training.
He said the available evidence suggests that adaptation develops through repeated, moderate heat exposure rather than a single sauna session, and that shorter sauna sessions followed by cooling and rehydration are likely to be the most sensible approach.
The evidence is less clear on whether sauna bathing can help manage heat once a heatwave has already begun. Professor Laukkanen noted that people in Finland continue to sauna bathe throughout the summer months, but warned that beginners need to exercise caution.
No medical guidance on sauna use in heatwaves
There is no medical guidance on using a sauna during a heatwave, and Professor Laukkanen stressed that heat adaptation is not the same as protection from heat. He said sauna should be viewed as one possible way of training the body's heat-regulation systems, rather than as a treatment or therapy for heatwaves themselves.
He said sauna should never replace standard public health advice, such as staying well hydrated, avoiding prolonged exposure during the hottest part of the day, seeking shade or cooler environments when needed, and paying particular attention to vulnerable people. Professor Laukkanen added that people with acute illness, fever, unstable cardiovascular disease, severe dehydration, or those who feel unwell should avoid sauna until they have recovered.
