Where heat could be the biggest threat for the World Cup

The 2026 FIFA World Cup could have excessive heat and humidity in some host cities in the U.S., Mexico and Canada, and it's an increasing risk in a warming world.

Starting on June 11, 104 matches involving 48 teams will be played in 16 host cities from southern Mexico to Canada, culminating in the July 19 final at MetLife Stadium in the New Jersey Meadowlands.

And since it's being played in two summer months, you can expect some issues with extreme heat, at times, in some venues.

FIFA's heat policy

International soccer's governing body, FIFA, has several measures they are implementing for this year's tournament:

• Mandatory three-minute cooling breaks in each half of each match
  
• Start times in hotter cities will be more often pushed into the evenings
  
• Fans can bring a full factory-sealed bottle of water into the stadium
  
• Cooled benches for players and other staff will be provided at all outdoor stadiums
  
• Misting systems, cooling bags and additional shaded areas can be set up during extreme heat
  

FIFA's trigger for its expanded heat policy is based on something called the wet bulb globe temperature (WBGT). This is a more comprehensive version of the heat index that also takes into account direct sunshine and wind speed. It's considered a more accurate measure of heat stress on people.

FIFA's emergency manual suggests a WBGT of about 90 degrees (32 degrees Celsius) is a threshold at which "precautions need to be taken to prevent any heat-related illness from occurring."

But some scientists think that threshold is too high.

In an open letter to FIFA on May 13, 21 experts specializing in climate and health urged FIFA to adopt more stringent criteria, including a lower wet bulb globe temperature threshold.

Which stadiums are most at risk?

We examined 30-year average data on high temperatures and dew points (a measure of how humid the air is) for all 16 sites during the time periods in which matches will be played at each site. We then calculated an "average heat index" for each site in that period and then ranked them based on that average heat index.

Three of those stadiums have both retractable roofs and air conditioning. We'll discuss those a bit later.

Two stadiums that will hold matches outdoors stood above all others for heat and humidity potential:

1. Miami
2. Monterrey, Mexico

Miami's average highs are around 90 degrees, and with dew points typically in the muggy low to mid-70s, their average heat index from mid-June through mid-July is about 102 degrees.

(MORE: Why dew point beats relative humidity)

What's more concerning is that six of the seven matches in Miami are scheduled to start in the late afternoon, sometimes just an hour or so after the hottest time of the day.

That includes their last two matches, a Round of 16 battle on July 11 and the Bronze final on July 18.

Monterrey, Mexico, is typically hotter, with average highs in the low to mid-90s. They've even had highs into the 110s on rare occasions.

They're not as muggy as South Florida, but average dew points in the upper 60s still push typical heat indices toward 100 degrees.

Fortunately, the four matches from mid- to late June in Monterrey are scheduled late in the evening, so evening temperatures should be at least a few degrees cooler than the daytime highs. But the heat could still be dangerous for both players and fans alike.

Three stadiums have air conditioning

The site with the most dangerous combination of heat and humidity in June and July is, by far, Houston.

Houston typically has similar oppressively muggy dew points (low to mid-70s) as South Florida, but is also a few degrees hotter (low-mid 90s).

Fortunately, the World Cup matches there will be played in NRG Stadium, with both a retractable roof and air conditioning. So, heat may be a concern outside the stadium, but not for the matches inside.

There are two other air-conditioned stadiums in the southern U.S. whose retractable roofs may be closed if it's hot and humid: AT&T Stadium in Arlington, Texas, and Mercedes-Benz Stadium in Atlanta.

Both typically have summer daytime heat indices in the 90s.

What heat is typical?

The animation below shows the average highs and dew points for all the World Cup sites. In general, dew points in the 70s are oppressively muggy, 60s are humid and 50s or below are considered comfortable.

You may notice some of those figures don't look all that hot or humid, particularly in Canada, the West, Northeast, or even in Mexico's capital city.

Mexico City isn't nearly as hot or humid because the city is at 7,200 feet elevation, almost 2,000 feet higher than Denver. While they have hit 90 degrees before in mid-June through early July, the thin, high-altitude air may be a bigger concern for players than the heat.

There are sneaky heat threats

All those temperatures in the maps above are averages, not forecasts. There can certainly be heat waves, even in typically cooler locations.

As of the time this article was published, NOAA's latest temperature outlook suggested hotter than average temperatures were expected for the first few days of the World Cup in the West, parts of the central, Northeast and South Florida.

That includes Foxborough, the New Jersey Meadowlands, Philadelphia, Miami, Kansas City, both California sites and Seattle.

The New Jersey Meadowlands and Philly average 18 and 26 days of highs at least in the 90s in June and July, respectively.

While SoFi Stadium in L.A. has a roof, it is also open air on its sides to allow typical cooler ocean breezes in. If a heat wave doesn't allow those cooling ocean breezes, it could get quite warm in the stadium, especially for matches scheduled in the afternoon.

For July, the latest outlook from The Weather Company and Atmospheric G2 indicates a higher than average chance of a heat wave from Northern California to the Pacific Northwest, as well as along the Gulf Coast, including Houston and Miami.

While that only adds to the concerns in Miami, it's also something to watch in both Seattle and Vancouver.

The late June 2021 heat wave rewrote the record books in the Northwest and western Canada, when highs soared above 100 degrees in Seattle for an unprecedented three straight days.

Vancouver's BC Place has a retractable roof, but no air conditioning. So, if one of these heat waves strikes, it could get warm and at least a bit humid if the retractable roof is closed.

Seattle's Lumen Field does not have a retractable roof. Its partial roof structure on its west and east sides can cover up to 70% of the stands, but leaves much of the field unshaded.

World Cup heat danger is trending higher

The risk of extreme heat affecting summer events like the World Cup is rising due to our warming climate.

According to a study from Climate Central released on June 3, extremely hot days in June and July are on the rise in 14 of the 16 World Cup host cities.

For example, Miami has averaged 12 such days a year since 2016, 10 more than they averaged from the mid-1980s through mid-1990s, Climate Central calculated.

Guadalajara, Mexico, doubled its June-July extreme heat days from five to 10 such days a year since the 1970s.

Climate Central used a threshold of 28 degrees Celsius (82.4 degrees Fahrenheit) to categorize extreme heat days. That was based on a 2017 study which found players in the 2014 World Cup in Brazil were impacted at temperatures above that level.

Jonathan Erdman is a senior meteorologist at weather.com and has been covering national and international weather since 1996. Extreme and bizarre weather are his favorite topics. Reach out to him on Bluesky, X (formerly Twitter) and Facebook.​

Kudos to Lisa Pringle for assistance with several maps in this article.