The 2026 World Cup, which starts this week in the United States, Mexico and Canada, arrives surrounded by warnings about extreme heat. Studies indicate that almost a quarter of the 104 matches may be played under conditions of high heat stress, which affects players’ performance and raises concerns about the health of athletes and fans.
The competition, the largest in history with 48 teams, spreads games across 16 cities with striking climatic contrasts. While some venues have air-conditioned stadiums or milder climates, others such as Miami, Houston, Dallas and Monterrey are expected to record high temperatures combined with high humidity during the northern hemisphere summer.
Surveys based on historical data and projections indicate that around 26 games can take place with a WBGT (Wet Bulb Globe Temperature) index of 26°C or higher. Another five face an even greater risk, above 28°C. This indicator considers not only air temperature, but also humidity, solar radiation and ventilation, offering a more accurate measure of the impact on the human body.
Thermal inequality between selections
The draw and calendar create different loads for teams. Tunisia, France, Ghana, Ecuador and Iraq appear among the most exposed to the heat in the group stage, according to an analysis by Bloomberg News. Uzbekistan, on the other hand, benefits from playing in closed, air-conditioned stadiums.
These climate variations require quick adaptation from players, who can switch between hot and controlled environments in a few days. Researchers highlight that fluctuations affect muscle recovery, resistance and technical performance, especially in the knockout stages.
WBGT, the indicator that guides alerts
The WBGT has become a reference for sports medicine specialists. When humidity is high, sweat evaporates less efficiently, making it difficult for the body to cool naturally. Even temperatures that seem bearable can generate significant risk in high-intensity activities such as football.
FIFA has introduced three-minute hydration breaks in each half of all games. However, critics consider the interval too short to produce a relevant effect in extreme conditions.
Criticism of FIFA protocols
A group of 21 health, sports medicine and climate experts sent an open letter to FIFA in May. They argue that current guidelines are insufficient and too permissive given the predicted scenario. The entity is under pressure to adopt stricter criteria for interrupting or postponing matches.
FIFPRO, the international players’ association, recommends longer breaks after certain WBGT levels and advocates postponing games above 28°C. The divergence with FIFA protocols gained strength as the tournament approached.
Climate change increases the risk
Researchers at World Weather Attribution estimate that global warming has made dangerous conditions much more likely compared to the 1994 World Cup, the last one hosted in the United States. The chance of extreme heat has increased significantly since then.
Recent heatwaves in Europe have reignited the debate over holding major sporting events in the summer. Meteorologists predict temperatures above the historical average in several tournament venues.
Recent experience reinforces fears
During the 2025 Club World Cup in the United States, complaints about heat and humidity were frequent. The German team, for example, reinforced its preparation at a training center in North Carolina to deal with the high temperatures.
Experts see the 2026 World Cup as a test of football’s ability to adapt to a hotter planet. Fans are also on the radar: many spend hours exposed to the sun without the medical facilities available to athletes. Elderly people and people with pre-existing conditions are more vulnerable.
FIFA’s decision to ban reusable bottles in stadiums has generated criticism, although the entity promises hydration points and cooling structures.
The weather appears as an invisible adversary that can influence results as much as talent and tactics. Even before the opening whistle, several teams are already preparing to face not only their rivals, but also one of the most challenging summers recorded in the host cities.