Two-thirds of the sites hosting the men’s football World Cup in North America could put players at very high risk of extreme heat stress, a study has warned.
Analysis published in the journal Scientific Reports looked at the 16 venues spread across Canada, the US and Mexico where the 2026 tournament will be held in June and July, when summer temperatures will be nearing their peak.
Researchers used data from the Copernicus Climate Change Service to model conditions for temperature, wind and humidity and an adjusted “universal thermal climate index” – a measure of how the human body responds to the environment – to simulate what footballers would experience on the pitch.
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“Our results indicate that 10 out of all 16 2026 Fifa World Cup venues are at very high risk of experiencing severe heat stress conditions,” the researchers from Poland and Germany said.
The study found the highest risk of thermal stress was in stadiums in Arlington and Houston in Texas, and Monterrey in Mexico, where the universal thermal climate index (UTCI) had values above 49.5C – although it did not take into account air conditioning, which is available in the US venues.
“When performing in warm and humid conditions, players’ heat production from intense physical activity often exceeds their ability to dissipate excessive heat, which may increase the risk of exertional heat illness.
“In response to prolonged exercise in a hot environment, intense sweating is triggered, which may result in dehydration of the body,” the study warned.
Staying in conditions where the UTCI was above 50C, as seen in the afternoon in Arlington and Houston, could put a “heavy burden on the body” and lead to heat exhaustion or even heat stroke, the researchers said.
To cope with high temperatures in Qatar, hosts of the 2022 World Cup, stadiums were air conditioned, additional breaks in each half were used and the entire event was postponed to the winter.
For the 2026 World Cup, the researchers said that for the safety of players it would be necessary to include measures such as regular additional water breaks.
They also advised organisers to plan the best time schedule of the matches for individual venues.
Failing to compensate for heat stress would not only threaten the health of players but also compromise their performance on the pitch, the researchers warned.
