For Norwegian nationals For the men’s soccer team, Saturday’s World Cup quarterfinal match against England will be a first in more ways than one. As the Scandinavian team prepares for the biggest game in its history, it will also face almost unimaginable conditions at home: South Florida’s harsh combination of heat, humidity and scorching sun that scientists warn can push the human body to its limits.

South Florida’s combination of strong sunshine, hot air temperatures and high humidity, driven by a plume of dusty air from the Sahara Desert crossing the Atlantic across the state, will put northern European players under a level of heat stress rarely experienced in their home countries.

Scientists quantify this heat stress by calculating the temperature of the wet globe. In addition to air temperature, the index takes into account humidity, which limits the evaporation of sweat from the skin; wind, which can act as a coolant; and solar intensity, since sunlight directly raises people’s core and skin temperatures.

Saturday’s game is forecast to be played at an extremely high WBGT of around 88 degrees Fahrenheit (31 degrees Celsius). The American College of Sports Medicine recommends that sports activities cease when this measurement exceeds 82 degrees Fahrenheit, because at this level, humans struggle to cool down and body temperature begins to rise rapidly. FIFA itself stipulates that if the WGBT exceeds 90 degrees Fahrenheit, players and referees must take breaks after 30 and 75 minutes of play to cool off with towels soaked in ice water.

While both teams will have been training to adapt to the environment, the conditions could make the match slower, according to Matt Maley, a researcher in ergonomics and environmental physiology at Loughborough University in the United Kingdom. He told WIRED: “In Miami this weekend, we may see players reduce the number of sprints or the distance they cover.” That would be a far cry from the fast-paced Premier League and energetic Eliteserien matches that English and Norwegian football fans are used to seeing.

But the real danger is ambition, Maley says. “Motivation sometimes replaces what the body tells the brain, so that’s when we get into the danger area, because people are so motivated to run the same distance, do the same number of sprints, and they could expose themselves to heat exhaustion.”

Miami, among other American locations, has become hotter in recent years as concrete and greenhouse gases released by burning fossil fuels trap heat.

A coalition of scientists from five continents warned FIFA and World Cup participants in May about the growing medical risks of heat stress. “We are concerned that FIFA’s current guidelines on heat stress mitigation are inadequate and will expose players to heat injuries at the 2026 Men’s World Cup,” they wrote in an open letter, noting that three-minute hydration breaks are too short for players to rehydrate and cool down. They recommended that the length of hydration breaks be doubled and that any games scheduled with a WBGT of 82 degrees Fahrenheit be postponed.

Fans also face dangers, including heat exhaustion, dehydration and heat stroke due to the stadium’s high levels of heat stress, New Weather Institute scientists warned in a report, adding that older fans and those with pre-existing health conditions are particularly at risk. They warned: “The 2026 World Cup heat stress crisis threatens to transform what should be football’s biggest celebration into a public health emergency.”