How Stars Are Beating the Extreme Heat at the 2026 World Cup

As a heatwave grips the United States, teams competing in the knockout stages of the World Cup face an additional challenge: staying cool.

Even before the tournament began, it was anticipated to be the hottest World Cup since 1994, the last time it was held in the U.S. With high humidity, thunderstorm risks, and temperatures expected to hover near or above 38 degrees Celsius across much of the country, simply managing the conditions could prove to be a crucial advantage.

Combating the heat extends far beyond mere hydration breaks during a match. In their opening tournament game against Mexico in Mexico City, the South African team lined up for the national anthem wearing what appeared to be silvery, loose-fitting jackets. Adding extra layers of clothing in extreme heat might seem counterintuitive. However, these jackets are part of Adidas's “Climacool” gear, specifically designed to reduce players' skin and core body temperatures. Beyond the jackets, the system includes cooling vests and boot covers.

“Managing body temperature and dealing with heat is one of the most important performance pillars we work on in innovation,” Margherita Raculia, Adidas's Director of Athlete Performance, told The Athletic.

Raculia stated that Adidas's innovation group began focusing on athlete cooling in 2012, and four years later, ahead of the Rio Olympics, they introduced their first cooling vest for athletes. Research was conducted with university partners and in Adidas's own innovation lab, which features a climate chamber to simulate various conditions. The goal was to work with professional and amateur athletes to understand how to more effectively reduce body temperature and enhance performance.

Climacool jackets were first spotted in Formula 1 in early 2025, when Mercedes drivers George Russell and Kimi Antonelli were photographed wearing them in Bahrain to combat the Middle Eastern heat. In the F1 paddock, they were dubbed “space jackets.” Both wore them over cooling vests. Adidas worked closely with Russell and Antonelli to tailor the Climacool gear to their needs and sizes. While similar cooling vests are common among drivers, wearing the jackets over them protects them from exposure to the high temperatures typical of the starting grid, where cars are already running. This keeps drivers as cool as possible before getting into their cars.

Feedback from Mercedes drivers and their physiotherapists to Adidas was positive, leading to the continued use of the gear through the end of the season and into 2026. This helped Adidas begin to consider how cooling technology could also be used at the World Cup. The company also took into account feedback from last year's Club World Cup, which was held in high temperatures in the U.S. last summer.

“We decided to redesign the cooling vest and jacket and adapt this technology for football,” Raculia said, “and then add an additional product that is not part of the Climacool system for Formula 1, but is designed for football — the cooling boot cover.”

Adidas worked closely with clubs, including Manchester United, Arsenal, and Juventus, in the run-up to the World Cup to adapt the Climacool gear for footballers. For them, vests need to be put on and taken off more frequently, typically during training and at halftime, unlike Formula 1 drivers who don't use them once they are in the car.

“We increased the coverage of the vest on the body to provide stronger cooling, which is important in football where players have short breaks,” Raculia said. “They then need to be able to quickly put on and take off the vest, so we added a front zipper. The vest is one-size-fits-all, but it needs to accommodate different body shapes and sizes, so there's adjustability on the sides to ensure optimal contact, which ultimately leads to optimal cooling.”

Adidas supplied the gear to 14 of the 48 participating nations, including Germany, Spain, Argentina, and Mexico, providing them with jackets, cooling vests, and boot covers for the tournament. The items are stored in freezer boxes to keep their temperatures low before use.

Similar to Mercedes drivers wearing the jackets for as long as possible before getting into the car, the World Cup versions are designed as “anthem jackets,” according to Raculia, so players can wear them during pre-match ceremonies. Raculia explained that the jackets are designed to create a “cooling microclimate” around the body. Being looser, they allow air to circulate inside, while the outer lining prevents cold air from escaping. The reflective surface prevents external temperatures from heating those wearing the jacket. “Function dictates design,” she added.

According to Adidas, the upper body gear can reduce core body temperature by up to 0.5ºC and skin temperature by up to 13ºC. The jacket and vest together weigh about one kilogram but are designed for close contact with the body. “For training purposes, the cooling effect outweighs the additional cost of carrying something heavy,” Raculia said.

The addition of the boot cover, which can be quickly slipped on and off over cleats or bare feet, came from Adidas's observations.

“We gathered data that foot temperature is a critical factor,” Raculia said. “An increase in foot temperature can lead to foot swelling and a less-than-ideal fit of the cleats, which can negatively impact comfort and performance.” The cover uses gel technology, which Adidas claims can cool feet by 2ºC within minutes. “They help with recovery,” Cruz said. “The idea is to put them on or keep them on during halftime in the locker rooms, so when players arrive or when temperatures are high, they can put them on, cool down, and lower their body temperature through their feet.”

While Adidas did not actively seek feedback during the tournament, Raculia said the visible use of the jackets, vests, and boot covers is “good validation” that the system is proving effective. She added that the Spanish team contacted Adidas in late June to provide “very positive feedback” on the system, with some players even requesting to keep it for individual use when they return to their club teams.

The technology, which began in Formula 1 and made its way to football, is now also targeting other sports. At Adidas, discussions are underway on how Climacool can be used or adapted in disciplines such as tennis, volleyball, hockey, or athletics. Raculia said there is “a very long list of Adidas athletes who want the system.”

And as heatwaves become more frequent globally, and sports adapt to higher temperatures, finding ways to better regulate body temperature and cool down will become increasingly important.

“This is important not only for professionals but also for us as consumers and ordinary, more amateur athletes,” Raculia said. “So this topic is not going away.”