Extreme heat will be one of the biggest challenges for players and fans during the 2026 FIFA World Cup. According to an analysis by the World Weather Attribution (WWA), around 25 percent of the 104 matches of the tournament could be played under temperatures that exceed the recommended thermal safety limits. The study points out that the probability of facing these conditions is almost double that recorded in the 1994 tournament held in the United States.

The projections were developed using a statistical model designed to calculate the probability of each match being played in extremely hot conditions. To assess the risk of physiological heat stress at host venues, the scientists used the wet-bulb globe temperature, known as WBGT. This indicator provides a more accurate measure of the thermal sensation experienced by the human body, because it incorporates not only ambient temperature, but variables such as humidity, solar radiation, and wind speed as well.

The analysis individually examined all the cities in the United States, Mexico, and Canada that will host 2026 World Cup matches. To do so, it considered specific local factors, including altitude, ambient humidity, regional climate, and the urban characteristics of each venue.

The researchers analyzed historical daily WBGT records for the period between June 11 and July 19, the scheduled dates of the tournament. They then compared these values with the safety limits set by FIFPro, the international soccer players’ union.

The organization set a WBGT index of 26° Celsius (78.8° Fahrenheit) as the threshold above which additional hydration and cooling measures would need to be implemented to protect the players. A temperature of 28° C (82.4° F) is considered high risk, the ceiling at which the organization recommended delaying or even suspending matches to avoid a potential health hazard.

Based on these parameters, the study concludes that one in four matches could be played under the first risk scenario, while at least five matches will be played in conditions equal to or above 82° F on the WBGT index.

The report warns that Miami, Kansas City, Philadelphia, Dallas, and Houston present a particularly worrisome scenario. The findings indicate that these cities have a return period of just one year for events reaching 82.4° Fahrenheit WBGT. In other words, there is a high probability that these extreme conditions will recur virtually every year during the World Cup dates.

The same frequency trend for the 78.8° Fahrenheit WBGT threshold is also observed in the US cities of Atlanta, Boston, and New York, as well as in the Mexican city of Monterrey.

The study stresses that the increase in these risks is closely related to the increasing global warming recorded in recent decades. In the case of matches held in 82.4° F, the probability of occurrence has at least doubled since 1994 in cities such as Los Angeles, Seattle, San Francisco, Monterrey, Toronto, and Vancouver, all of which are hosting games in this World Cup.

Rubén del Campo, spokesman for Spain’s State Meteorological Agency, explained to SMC Spain that, since 1994, the global average temperature has increased by between 0.5 and 0.7 degrees Celsius. “It is a figure that may not seem very high, but it represents approximately half of the warming observed in the last century and a half. Moreover, since the mid-1990s, when the previous World Cup was held in the United States, the effects of climate change have intensified all over the planet, especially heat waves,” del Campo told SMC Spain.

The 2026 World Cup Will Be Played in Stifling Heat

The WWA report joins other recent research that warns of extreme weather conditions predicted for the World Cup. At the end of 2024, a study published in the journal Scientific Reports warned that 10 of the 16 host stadiums present a “very high” risk of extreme heat, and that two of them could particularly affect players and attendees.

According to this research, the stadiums with the highest risk of generating severe heat stress are those of Arlington and Houston, both in Texas, as well as the BBVA Stadium in Monterrey.

“This set of studies underscores the need to plan ahead for major events such as the World Cup, as well as implement proactive policies to mitigate heat. As the WBGT index only considers environmental conditions and does not incorporate sport’s own metabolic heat production or the insulating effects of clothing, which can limit heat loss, more advanced models and predictive tools are required to ensure the safety of athletes,” Julien Périard, director of the Institute of Sport and Exercise Research at the University of Canberra, told SMC Spain.

FIFA maintains that the 2026 World Cup match schedule was designed based on a technical analysis of all venues, which took into account factors such as average temperatures, cooling infrastructure, public transport, and security conditions.

In response to warnings about high temperatures, the sporting body announced the implementation of three-minute hydration breaks at the halfway point of each half in all tournament matches.

However, WWA specialists believe that this measure should be accompanied by other preventive strategies, including adjustments to the warm-up times for players, improvements in infrastructure and cooling systems in stadiums, and stricter medical supervision during matches for both players and fans.

This article originally appeared on WIRED en Español and has been translated from Spanish.