In an open letter, 20 international experts say the governing body’s approach is “inadequate” and “impossible to justify”, urging urgent reforms before the tournament kicks off across the United States, Canada, and Mexico.
The scientists argue that rising temperatures across host cities could expose athletes to extreme physiological strain, especially when heat, humidity, wind, and solar radiation are combined into measures of thermal stress.
Rising Heat Risk Across Host Cities Raises Alarm
Research cited in the letter suggests that 14 of the 16 stadiums selected for the tournament could experience temperatures that exceed safe thresholds during summer matches.
In parts of the southern United States and northern Mexico, daytime highs typically sit in the low-to-mid 30°C range, with spikes approaching 40°C during heatwaves.
When measured using the Wet Bulb Globe Temperature (WBGT)—a standard that accounts for humidity and environmental conditions—scientists warn that players in several host cities could regularly face “extreme” heat stress conditions.
According to analysis by World Weather Attribution, approximately a quarter of matches may be played above 26°C WBGT, with some fixtures potentially reaching or exceeding 28°C WBGT, a level widely considered dangerous for elite performance.
Current FIFA Measures Under Scrutiny
FIFA maintains that it is actively preparing for climate risks, stating it is “committed to protecting the health and safety of players, referees, fans, volunteers and staff” as part of its tournament planning.
At present, the organisation has introduced several safeguards, including mandatory three-minute cooling breaks in each half of matches, regardless of conditions. It also plans to use climate-controlled benches for substitutes and technical staff.
FIFA’s guidelines rely on WBGT readings, with around 28°C considered a critical threshold where heat stress becomes a serious concern. Its emergency care manual notes that when readings approach or exceed 32°C, organisers should determine “what precautions need to be taken to prevent any heat-related illness from occurring”.
Fan protections include shaded areas, misting systems, cooling buses, expanded water stations, and permission for spectators to bring factory-sealed water bottles into venues.
Scientists Call for Stronger Protections and Rule Changes
The signatories of the letter include researchers from the UK, US, Canada, Australia, and Europe, many of whom specialise in environmental stress and athlete safety.
They are calling for immediate changes, including delaying or postponing matches when WBGT exceeds 28°C, extending cooling breaks from three minutes to at least six, and upgrading sideline cooling infrastructure.
They also recommend that FIFPRO safety standards be adopted, alongside continuous updates to heat policies as climate science evolves.
Professor Douglas Casa of the University of Connecticut stressed the need for longer recovery periods, stating:
“The hydration break in each half absolutely needs to be longer than three minutes - at least five minutes for each break and preferably six.”
He added that stronger action is needed before the tournament begins, not during it.
“Reckless with Player Health,” Experts Warn
Andrew Simms of the New Weather Institute, who coordinated the letter, said the stakes are immediate and potentially severe.
“Player safety is an immediate and urgent concern because things can go wrong very quickly when people overheat,” he said.
He went further, warning: “We’re worried that Fifa is playing recklessly with the health and safety of players.”
The experts argue that without stronger safeguards, elite athletes could face avoidable risks such as heat exhaustion, dehydration, and in extreme cases, life-threatening heat illness.
FIFA Defends Planning and Real-Time Monitoring
In response, FIFA declined to directly address the letter but said it will apply a “tiered heat mitigation model” throughout the tournament, adjusting measures based on real-time conditions.
The organisation said it will deploy dedicated meteorological teams across host cities, using WBGT and heat index data to guide decisions on scheduling and match safety.
FIFA also noted that kick-off times have been adjusted to avoid peak heat where possible, warmer venues may host matches in covered stadiums, and scheduling has been designed to reduce travel strain and increase rest periods.
It added that it will continue working with medical experts and local authorities to ensure what it described as a “safe and resilient” World Cup.
Climate Pressure Looms Over 2026 Tournament
Beyond heat, scientists also warn that thunderstorms, wildfire smoke, and fluctuating air quality could complicate conditions across North America during the summer tournament.
Researchers say climate change has already increased the likelihood of extreme heat events compared to previous tournaments held in the region, intensifying concerns about athlete welfare as global sporting events increasingly face environmental stress.