Nearly one in five World Cup matches reached heat levels players’ union warns against

Guardian analysis finds 19% of games reached heat levels warranting delays, as Fifa defends its player safeguards

The climate crisis has come for football.

During this year’s World Cup , nearly one in five of the tournament’s 100-plus matches took place in levels of heat and humidity that a football players’ union has previously said should trigger delays or postponements, a Guardian analysis has found. An additional 23 matches were played in cities as they reached those heat levels, but in stadiums where conditions were mitigated by air conditioning.

“The climate crisis is hitting the things we all need, like a stable climate, clean air and affordable food, as well as the things we love, like football and other sports,” Simon Stiell, executive secretary for the United Nations climate body, said in an emailed comment.

Our analysis looked at conditions where the tournament’s 104 matches were either already played (102) or the forecasts for the two remaining matches.

The findings are a sign of a broader challenge facing football as the planet warms. The climate crisis is making extreme heat more frequent and intense, raising new questions about whether the conditions in which major tournaments are played can remain safe for players and supporters.

“The 2026 Fifa World Cup matches have introduced a true stress test of heat mitigation and preparedness,” said Joshua L DeVincenzo, an assistant director at Columbia University’s National Center for Disaster Preparedness. “Fifa, spectators, stadium operators, and others … were tested firsthand on the disruptions and complications that extreme heat and weather can pose.”

The findings come as a record-breaking heatwave scorches much of the United States, with more than 125 million Americans spanning from California to New England under dangerous heat alerts. Sunday’s final seems set to be played in conditions with a wet bulb globe temperature estimate of just under 26C (79F), with low humidity alleviating the effects of high air temperatures. However, another climate-fueled concern could plague attenders: Wildfire smoke is expected to continue to degrade air quality in the region, with New York City mayor, Zohran Mamdani, warning of health impacts.

Our analysis found that an estimated 20 matches were played in conditions with wet bulb globe temperatures (WBGT) that may have been at or over 28C (82F).

Under those conditions, the players’ union Fifpro has argued , games should be delayed or postponed to protect footballers’ health. Other match attenders can also face risks, said DeVincenzo.

“We learned from this World Cup that, in addition to player safety and health, important precautions must be considered for spectators, volunteers and stadium staff long before the day of the match,” he said.

Fifa did not respond to a request for comment. The organization previously told the Guardian it had been stationing meteorologists at match venues to help prepare for extreme weather, and that tournament planning included “close coordination” with host city organizers as well as stadium authorities and national agencies. Players this year were given mandatory hydration breaks, and being provided access to water, electrolyte drinks, ice, cold towels, fans, mist and shade, Fifa has said.

Fifpro declined to comment on the latest analysis, but previously told the Guardian: “The lesson for everyone in the industry is that with a warming planet, heat conditions will play a bigger part in tournament and league scheduling decisions in the future.”

WBGT readings account for humidity, direct sunlight and wind to provide a more accurate measure of heat stress and the body’s ability to cool itself through sweating. At high enough levels of heat and humidity, sweat can no longer evaporate efficiently, preventing the body from cooling itself and leading to rapid overheating that can cause heat illness or even death.

Official WBGT measurements require specialized equipment on site, but the Guardian compiled approximations based on air temperature and humidity data for the time and place of each match, with data from the open-source weather service Open-Meteo. Estimates were calculated using a formula created by the Australian Bureau of Meteorology and used by institutions including the Canadian military .

The hottest game played in a non-air-conditioned stadium was held on the Fourth of July in Philadelphia. During the France v Paraguay round of 16 match, temperatures at the city’s stadium reportedly reached 38C (100F), and WBGT during the game may have reached or exceeded 33.9C (93F), the Guardian’s analysis found.

The hottest game overall was played when Argentina defeated Austria 2-0 on 22 June in Dallas, Texas. Though the game was played in one of the only three fully air-conditioned World Cup 2026 stadiums (the other two being in Houston, Texas and Atlanta, Georgia), the Dallas match still exposed those outside the venue to sweltering conditions. The asphalt outside the stadium, for instance, reportedly reached a sizzling and dangerous 50C (122F).

More must be done to protect those outside World Cup venues, said DeVincenzo, including those entering and exiting matches, or attending fan festival gatherings.

“Spectator experiences created a secondary risk in the heat; factors such as long walking distances without cover, unshaded areas, sun-exposed seating in the stadium, and long wait times in heat-emitting spaces like parking lots put people at a much higher risk of heat stress and related injuries,” he said. “These experiences can be addressed ahead of future games by training volunteers to identify signs of heat stress and to know the appropriate actions to take when fans experience dizziness, fainting, or falls.”

Every match played in three cities – Dallas, Houston and Miami – appears to have been contested in conditions that breached the 33.9C threshold. At the Miami, which does not have air conditioning, players, workers and spectators alike blistered under WGBT readings of approximately 32.5C (90.5F) during Norway’s match against England last weekend. Temperatures reached 33C (91.4F) with 65% humidity, and sweat poured off of every face in the venue.

Record-breaking heat and humidity are set to blanket the midwestern and eastern US this week, potentially making conditions even more challenging for players and fans at some games. In the future, conditions could deteriorate even further.

The 2030 World Cup, for instance, is set to be staged across Spain, Portugal and Morocco, each of which is already experiencing significantly more extreme heat due to the climate crisis. Four years later, Saudi Arabia is expected to host the 2034 tournament during the northern hemisphere winter, a scheduling shift designed to avoid summer temperatures that regularly climb above 40C (104F).