As the 2026 World Cup approaches, research tied to Imperial College London warns more matches than in 1994 could be played in unsafe heat across 16 U.S., Mexico, and Canada host cities—raising alarm over whether FIFA’s existing thresholds and cooling plans are
On a hot day, players can feel it before the numbers do. Sávio Bortolini Pimentel, who nearly made Brazil’s roster for the 1994 FIFA World Cup, still remembers the way the heat changed the match.
He was 20 and playing for Flamengo in Rio de Janeiro when teammates told him after the fact that conditions during some games were “intense.” The final at the Rose Bowl in Pasadena, California—on a 90 degree day—was among the most punishing, with Brazil prevailing over Italy.
Now, with the 2026 FIFA World Cup set for June and July, the warning is starker. Researchers at Imperial College London estimate that human-driven climate change has made unsafe temperatures significantly more likely in the tournament’s 16 host cities across the United States. Mexico. and Canada. And they predict a higher number of games could cross into dangerous heat than in 1994.
In extreme conditions, the body can’t simply “push through” the way sports culture often demands. “In extreme heat, it becomes impossible to play with the same intensity,” one of the researchers’ accounts of the risk emphasizes—an impact that lands on the pitch in fatigue, cramps, and slower play.
The Imperial College report modeled heat risk using a wet bulb globe temperature threshold of 83 F. a measure recommended by FIFPRO. the international player’s union. Wet bulb globe temperatures are calculated using sun, humidity, and temperature to reflect the stress on the human body. The report projects that five games could be played in unsafe heat, up from three games in 1994.
But the gulf between how players’ unions define risk and how FIFA currently decides to act is part of the tension. FIFA uses wet bulb globe temperatures as well, but it currently considers postponing matches only at levels exceeding 90.
Chris Mullington. a consultant anesthetist at Imperial College London who presented the report at a webinar. explained why the wet bulb approach matters. “A 30 C [86 F] day in dry. breezy conditions is very different from a 30 C [86 F] day with high humidity. strong sun. and little wind. ” he said. “High humidity reduces the evaporation of sweat, limiting the body’s primary cooling mechanism.”.
That isn’t an academic distinction to players. In an open letter. 60 current and former professional soccer players from around the world urged FIFA to update its heat guidelines for events held during dangerous heat before the World Cup. They described what unsafe conditions can do to a person in motion: “It can make you feel light-headed. dizzy. experience fatigue. muscle cramps and worse. You can run less and it becomes impossible to play with the same intensity as with more average temperatures.”.
They also pressed FIFA to address the climate crisis beyond match-day decisions, asking the league to drop fossil fuel sponsors and change game schedules in ways that could reduce travel and the league’s fossil fuel footprint.
Friederike Otto. professor of climate science at Imperial College London and one of the report’s authors. framed the stakes in terms of viability. She said the increased risk for hotter temperatures shows climate change is affecting whether World Cups can even be held during the northern hemisphere summer. The final match of the tournament is scheduled for July 19 at MetLife Stadium in New Jersey. In the report’s projections, it carries a 12.5 percent chance of exceeding the 79 mark and a 3 percent chance of reaching 83.
Otto said the risk of “cancellation-level” heat for the World Cup final should be a warning sign. “That the World Cup Final itself—one of the biggest sporting occasions on the planet—faces a non-insignificant risk of being played in ‘cancellation-level’ heat should be a wake-up call for FIFA and fans. highlighting the urgent need to realize that there is no aspect of society not affected by climate change. ” she said.
The contrast with past tournaments is difficult to ignore. The 2022 World Cup in Qatar was moved from summer to winter because of the threat of extreme heat. Last summer’s Club World Cup—held in 12 locations around the United States—served as a kind of prelude. and yet no games were postponed due to heat even though temperatures soared above 90.
Training, experts say, can only go so far. In the heat, “it’s increasingly demanding. The pace is automatically reduced.” Douglas Casa. chief executive officer of the Korey Stringer Institute. a nonprofit based at the University of Connecticut. described what severe heat does to the body during exercise: athletes’ heart rates rise. muscles fatigue faster. and sweat production increases as the body tries to prevent a rapid rise in core temperature.
Under severe heat and dehydration, Casa said, around 104 degrees, the body enters a volitional exhaustion phase—the point during exercise when a person stops because they feel unable to continue doing the same movements.
On the field, that turns strategy into something colder than tactics. Casa put it plainly: “The game turns into a different game, it’s more ‘mentality.’ The one that commits less mistakes is the one that ends up winning.”
Sávio. now retired and a former bronze medalist with Brazil at the 1996 Summer Olympics in Atlanta. said today’s players may be better prepared than those in 1994. and he points to evolution in preparation techniques. equipment. and products. “There are athletes that are more used to the cold than to the heat—that’s normal,” he said. “But today’s athletes are much more prepared. and even more so than in 1994. due to the evolution of preparation techniques. equipment. and products.”.
Still, he warned that preparation doesn’t erase the sensory reality of heat on the pitch. “If we’re looking at 35 degrees C [95 F]. like what happened in 1994 when we even heard of matches played at 40 degrees C [104 F]. then yes. it’s increasingly demanding. ” he said. “The pace is automatically reduced.”.
Casa argued that even if FIFA chooses not to postpone matches, it should build stronger cooling options into stadium operations. He urged FIFA to make aggressive cooling strategies available at all stadium locker rooms. He recommended extending hydration breaks from the mandated three minutes to six. saying the heat can affect recovery from one game to the next.
“Do you realize people could easily be 103 or 104 degrees when they come in at halftime?” Casa said. “My point is. if you have 15 minutes and you get in quickly at the stoppage. you could have 10 or 11 minutes of aggressive cooling: rotating freezing cold wet towels over your whole body. going into a cold plunge. anything like that.”.
Casa said he is not opposed to playing in hot weather. But he argued that high temperatures and dehydration at the World Cup can lead to lower-quality soccer.
“Why not give the fans who just spent a fortune on these tickets the best quality game that they could possibly watch with these elite soccer players?” he asked.
For fans, the heat debate isn’t only about the athletes. Kevin Muneton Ramirez. a 27-year-old American-Colombian dual citizen. is planning to watch Cristiano Ronaldo in what is expected to be his last World Cup. He bought tickets for the June 27 match in Miami between Portugal and Colombia and said he expects his home country’s team to win.
Muneton Ramirez said, as a fan, he doesn’t mind games where exhaustion shows up late. “The game turns into a different game, it’s more ‘mentality,’” he said. “The one that commits less mistakes is the one that ends up winning.”
But Casa argued that FIFA should at least provide free water-filling stations inside stadiums, because overwhelming heat and dehydration can make fans sick even when they are not moving much.
That recommendation collides with a specific rule change described in FIFA’s recently updated stadium code of conduct. According to the code of conduct, fans, “for the avoidance of doubt,” are no longer allowed to bring in an empty bottle that can be refilled at a water fountain or dispenser.
Muneton Ramirez said he does not usually attend soccer stadiums. “But if I have the opportunity to go to a World Cup … at least once in my lifetime, I’d go to any game,” he said.
The season is still unfolding. the World Cup is still months away. and the heat hasn’t arrived everywhere at once. But the numbers—and the thresholds—are already pressing. The Central question now isn’t whether heat will be a factor. It’s whether FIFA’s decision points. cooling plans. and rules for stadium life are built for a world where unsafe conditions are coming more often. and more predictably. to summer sports.
2026 World Cup FIFA extreme heat wet bulb globe temperature FIFPRO Imperial College London MetLife Stadium player safety sports climate risk Korey Stringer Institute hydration breaks stadium code of conduct