A severe heat dome has settled over the East Coast of North America as the FIFA World Cup enters its knockout stages.
Climate Central says the heatwave, at its peak, was made at least five times more likely by climate change.
Matches in cities including Houston, Dallas, Miami and Philadelphia are expected to face dangerously hot conditions for players, fans and stadium workers.
Researchers say the rising heat risk is forcing sports bodies to rethink when, where and how major outdoor tournaments can safely be held.
A severe heat dome has settled over the east coast of North America as the FIFA World Cup enters its knockout stages, pushing several host cities into conditions researchers say are dangerously hot for players, fans and stadium workers. New analysis from Climate Central found that the heatwave, at its peak, has been made at least five times more likely because of climate change.
This is only the latest sign of a pattern that has been building since long before this tournament kicked off. Host cities have been running 0.7 degrees Celsius (°C) warmer than they were in 1994, the last time the United States hosted the World Cup.
“Several of this week’s matches, including those in Houston, Dallas and Miami, are forecast to occur in conditions where wet bulb globe temperature is expected to approach or exceed thresholds we know push the limits of the body’s ability to cool itself, especially during sustained physical exertion,” said Luke Parsons, a heat expert at environmental organisation The Nature Conservancy.
Wet bulb globe temperature measures heat stress by combining temperature, humidity, radiant heat and wind. It is used to assess how much strain the body is under, especially during physical exertion.
These rising temperatures have been pushing outdoor sports of every kind closer to the physiological limits of the human body, forcing tournaments, leagues and governing bodies to rethink when, where and how competitions can safely be held.
The risk extends beyond the pitch. Fans, stadium workers, security staff and broadcasters also face heightened exposure, especially during daytime fixtures, long queues and travel to and from venues.
“For fans, the high temperatures mean heat risk doesn’t end at the stadium gates. Getting to and from the venue, waiting in lines, and tailgating in direct sun can be just as dangerous as time in the stands. Outside in the sun, it’s not just uncomfortably hot for sustained intense activity — it’s dangerously hot,” said Parsons.
A separate analysis earlier by climate news organisation Climate Central had found that 97 of the 104 matches face a higher probability of “performance-impairing heat” above 28°C, with nearly half of all matches carrying at least a 50 per cent likelihood of such conditions.
This weekend’s heat dome shows that warning coming true. Several of the tournament’s knockout-stage venues are now living through the conditions researchers had flagged earlier.
“I think we can very confidently now say that every heatwave that is occurring today has been made more intense and more likely because of climate change. There is no doubt that climate change is really an absolute game changer when it comes to heatwaves,” said Fredi Otto of World Weather Attribution.
Venues without air conditioning,including those in Toronto, Miami and Philadelphia, are facing the sharpest conditions this week. Miami’s Argentina-Cape Verde match on July 3 was forecast at 86.6°F (30.3°C), with climate change having made the underlying humid heat at least ten times more likely. Philadelphia’s Paraguay-France match on July 4 was forecast to reach 96.3°F (35.7°C) — nearly 5.6 degrees Celsius (°C) above normal – again with the heat made roughly seven times more likely.
By contrast, teams drawing matches in Mexico City on July 5 and Vancouver on July 7 face comparatively mild conditions. The fixture venue list was now beginning to look, to some observers, like a competitive disadvantage compared to teams competing in a few air conditioned stadiums.
Climate scientists and sports physiologists have been documenting heat’s impact on elite competition across disciplines and continents.
At the 2026 Australian Open (tennis tournament), temperatures nearing 40°C triggered the tournament’s extreme-heat policy, suspending outdoor matches and shifting play into roofed arenas.
Ollie Jay, professor of heat and health at the University of Sydney, has pointed out that extreme heat forced Australian Open tennis players to collapse in 2014 and again in 2018, pushed equestrian events at the Tokyo Olympics into cooler evening hours, and has repeatedly forced football tournaments to introduce hydration breaks.
Meanwhile, Cricket Australia now runs a dedicated heat stress index with separate calculators for adult and adolescent players, while Australia’s National Rugby League has introduced extended half-time breaks guided by its own heat stress tool.