As the FIFA World Cup 2026 kicks off in Mexico City this Thursday, June 11, a new briefing from UN Climate Change has revealed that extreme heat could affect more than a quarter of all 104 tournament matches, raising urgent questions about player safety and how football will be played across three host nations.
The analysis, published on June 9 by UN Climate Change in partnership with leading sports scientists, found that 26 of the 104 scheduled matches are likely to be played in hazardous heat conditions. Of those, five are projected to reach heat levels that should force postponement under medical guidelines.
The findings come as 48 teams prepare for the largest World Cup ever staged, with games spread across 16 cities in the United States, Mexico and Canada over nearly six weeks through to the July 19 final.
Hazardous heat is measured by the Wet Bulb Globe Temperature (WBGT), with the danger threshold set at 26 degrees WBGT, equivalent to approximately 40 degrees Celsius air temperature combined with 30 per cent relative humidity. At 25 degrees WBGT, research shows a 12 per cent reduction in athletic performance, with cardiovascular function, muscle function and central nervous system function all significantly affected.
FIFA has set the match suspension threshold at 32 degrees WBGT. However, global players' union FIFPRO has publicly stated that matches should be delayed or postponed once the WBGT reaches 28 degrees, calling FIFA's 32-degree limit an unsafe level of heat strain for professional athletes.
Simon Stiell, Executive Secretary of UN Climate Change, said the impact extends well beyond elite sport.
"We're all watching the game, but it's stopped, because it's too hot. Hot for players, for fans, for everyone. It's hot and getting hotter. That's not random. That's climate change," Stiell said in a statement accompanying the briefing.
The practical implications for players are significant. Star attackers like France's Kylian Mbappe, who faces Senegal on June 16 in New Jersey, and South Korea captain Son Heung-min, whose Tottenham Hotspur and national team duties have kept him at peak physical condition, will see their explosive pace and high-intensity running capacity diminished in extreme heat. Bayern Munich winger Michael Olise, who scored a hat trick in France's pre-tournament friendly and enters the World Cup with seven goals in 17 appearances for Les Bleus, will need to manage his energy output carefully in potentially dangerous conditions.
Climate scientists note that since FIFA staged the 1994 World Cup in the same US venues, climate change has more than doubled the likelihood of extreme heat events. What was once considered exceptional summer weather in cities like Dallas, Houston and Phoenix has become increasingly routine.
The inevitable consequence will be visible player fatigue, reduced match intensity and altered tactical approaches, particularly in afternoon kickoffs in southern US and Mexican venues. Teams from temperate climates, including several Asian representatives, may find the conditions especially challenging as they adapt from domestic leagues played in cooler environments.
FIFPRO has called for mandatory cooling breaks and stronger heat protocols, while tournament organisers have confirmed that water breaks will be enforced in all matches played above predetermined WBGT thresholds.
The gap between FIFA's 32-degree suspension threshold and FIFPRO's recommended 28-degree intervention point remains a point of contention and will likely be scrutinised closely once the first matches are played in the southern US heat this week.
Sources: InsideWorldFootball, UN Climate Change, AP News, FIFPRO
