Sites of 2026 FIFA World Cup pose heat stress threats for players at various North American locations

(NEW YORK) — Extreme heat could pose a significant threat to players and spectators at the next World Cup, according to climate and medical experts.

The 2026 FIFA Men’s World Cup will take place in the summer of 2026 in North America — during the hottest part of the year — and several of the venues could prove to be unsafe for players during the middle of the day, when the sun will be at its highest, according to a study published in Scientific Reports on Thursday.

“The Championship will be held over a huge area, in several climate zones, so it will be a challenge for the soccer players taking part in the tournament, due to the need for quick adaptation to diverse local climate conditions,” Kate Lindner-Cendrowska, a researcher at the Institute of Geography and Spatial Organization at the Polish Academy of Sciences and an author of the study, told ABC News.

Footballers competing in the tournament may be at risk of severe heat stress and dehydration at 10 of the 16 host cities, the researchers found after analyzing historical weather data from 2009 to 2023 from Copernicus, Europe’s Climate Change Service, to mimic the temperature, wind and humidity from mid-June through mid-July observed at each of the 16 World Cup locations.

To simulate the pitch conditions that footballers would experience during a match, values were then adjusted for the Universal Thermal Climate Index — a measure of how the human body responds to the outdoor environment.

The sites with the highest risk were found to be in Monterrey, Mexico; Arlington, Texas; and Houston — which had suggested average hourly UTCI values above 49.5 degrees Celsius, or 121.1 degrees Fahrenheit, the researchers found. The dataset assumes that the stadiums are not air conditioned or that other measures are taken, which would reduce levels of water loss and heat stress in some scenarios, according to the researchers.

AT&T Stadium in Arlington, Hard Rock Stadium in Miami and NRG Stadium in Houston are all air-conditioned — as is Estadio Monterrey in Mexico. But all of those locations are typically hot and humid during the summer months, and global warming is expanding the regions in which heat stress is a concern.

During a Copa America game played in Kansas City in June, a referee collapsed from apparent heat illness as the heat index hovered at 100 degrees Fahrenheit.

“I think we already have the context for the 2026 FIFA World Cup because we just witnessed the Copa America tournament in North America,” Jessica Murfree, assistant professor of sports administration at the University of North Carolina at Chapel Hill, told ABC News. “I think that that competition serves as an excellent litmus test on heat related risks that we will be able to expect in 2026.”

Heat illness typically results from a combination of factors, such as high ambient temperatures, humidity, physical activity and inadequate fluid intake, according to Copernicus.

During sports competitions that involve intense physical activity, such as soccer, players can experience significant thermoregulatory strain, which may be further intensified by the thermal environment, Lindner-Cendrowska said. In addition, in response to prolonged exercise in a hot environment, intense sweating is triggered, which may result in dehydration of the body, she added. Soccer is especially labor-intensive, because players exert physicality “full-on” for 45 minutes until halftime with little breaks, Murfree said.

“In [a] hot environment, it is difficult to remove the excess heat from the body, what may lead to fatigue, overheating of the athletes’ body and exertional heat illnesses,” she said. “It is a particular serious threat for highly motivated athletes, because they have very limited options for compensation during the long-term competitions.”

Heat impacts over a long period of time can even go beyond that, Kai Chen, an associate professor of epidemiology at the Yale School of Public Health, told ABC News. High temperatures can affect the cardiovascular system, leading to heart attacks and stroke as well as other systems of diseases, such as kidney failure and mental health disorders, such as depression, anxiety and more suicide attempts, Chen said.

“The adverse impacts of heat on the human body is really substantial,” Chen said, adding that heat is the leading weather-related killer, per the Centers for Disease Control and Prevention.

The 2026 World Cup will take place across Canada, Mexico and the U.S. between June 11 and July 19, 2026, when summer temperatures across North America are nearing their average peak. If the last few summers are any indication, 2026 will likely follow the trend of record-breaking heat, Chen said.

“We know temperatures in the mainland U.S. have been increasing,” he said. “Unfortunately with a warming climate, the trend is going to increase.”

Scheduling games with the intent to prevent heat stress will be of the utmost importance, the researchers said.

The highest thermal stress at all stadiums is estimated to occur from 2 p.m. to 5 p.m. local time. The one exception was in Miami, which observed a longer time frame, with its highest UTCI values between 11 a.m. and midday.

Past studies on former World Cup venues have highlighted the negative effects for players who compete in high relative humidities, including in Brazil in 2014.

The continued heat coverage may bring more attention to the climate crisis, as international fans see their favorite sports stars suffering from the impacts of extreme heat, Murfree said.

“Sports has this massive, transformative platform to move people into climate action in ways that other systems don’t,” she said.