Extreme heat stress at the FIFA World Cup 2026: Health risks expected for players and spectators due to high temperatures
On hot summer days and during sport, we need to drink enough and make sure we keep our body temperature stable. This also applies to the footballers at the 2026 World Cup in North America. Very high temperatures are expected at this World Cup. Peter Bröde from the Leibniz Research Centre for Working Environment and Human Factors in Dortmund (IfADo), together with colleagues from the Polish Universities of Warsaw and Wrocław, and the German company ErgonSim in Meßstetten, has studied the effects this will have on the athletes.
Considering air temperature alone is not enough to determine the heat stress on people. Besides wind and solar radiation, humidity is another decisive factor, as it determines how well sweat can evaporate on the skin and provide cooling. The lowered oxygen content of the inhaled air at high altitudes has a direct influence on performance. And finally, our body produces heat itself when we are active. The researchers have incorporated all these and other factors into their model.
Recommended breaks to drink and games in the morning and evening hours
The unit for heat stress assessment in this research is the UTCI (Universal Thermal Climate Index). This index relates the influence of air temperature, humidity, wind speed, solar radiation, clothing insulation and body heat production on the heat stress on an average day, which was determined from historical weather data. The researchers identified a UTCI value of 49.5 degrees Celsius as the tipping point above which accelerated heating of the body occurs. This value will most probably be reached in Arlington, Houston (USA) and Monterrey (Mexico). A critical fluid loss of more than 1.5 kilogram per hour is also to be expected in these locations. Overall, there is a very high risk of extreme heat stress in 10 of the 16 stadiums. The researchers therefore recommend that drinking breaks be made possible during matches and that matches are scheduled to the morning and evening hours.
However, not only the active players are affected by the consequences of heat stress. Spectators, especially children and more vulnerable people, are also at risk, as they usually are less fit than the athletes and therefore less able to cope with heat stress. Athletes recovering from previous heat stress or minor injuries are also more likely to suffer heat stroke or other types of heat illness. Therefore, pre-cautionary planning is essential for ensuring that the World Cup is going to be a great football experience for everyone.