Tennis Matches Are Heating Up, Literally. Here’s How the Court Became a Living Laboratory for Managing Extreme Temperatures

As I drew back my racket to rip a forehand down the line, it felt like my reaction time had slipped into slow motion and my legs were turning to Jell-O. I watched the ball drop into the net. Trying to understand how my one tennis weapon had become a weakness in a matter of minutes, I glanced at the thermometer.

After blowing through five packs of electrolytes in the dry Arizona heat in June, I flew back home to cool, coastal Maine with a headache that lasted for three days. The heat-absorbing hard-court tennis surface can soar some 30 degrees higher than the air temperature around it. Playing in these conditions without balancing your water and electrolyte intake can become, in the sport’s terms, an ill-fated double fault.

The dangers of oppressive heat were in full view at the Cincinnati Open this month, when world No. 5 player Novak Djokovic collapsed mid-match, as the heat exacerbated a chronic health condition. The incident led to criticism about scheduling matches in peak heat. In July at the Memphis Classic, Ekaterina Alexandrova was wheeled off the court due to heat-related illness.

Even on the cooler clay surface at the French Open in May, when a heat dome trapped hot air over the region, Jakub Menšík keeled over at the end of a five-set win, as fans left their scorching seats to crowd under the court sprinklers. Tennis is pushing athletes’ physiological limits in a rapidly warming world. In many ways, it’s the nature of the game—intense, quick sprints and powerful swings, followed by short changeover breaks on such a sizzling surface—that can quickly raise a player’s metabolic rate and make it very hard to cool down.

For the past two decades, scientists have increasingly looked at a whole-body approach to managing heat on the court—one that goes beyond simply guzzling water. The hard-court surface, in a sense, has become a laboratory for heat stress management. Open in Queens, New York, which began this year on August 23, that risk has risen from 49 percent in the 1970s to 67 percent.

Greenhouse gases are warming the planet, and by extension, changing the rules of court. After seven match retirements from the October 2025 Shanghai Masters, followed by fierce disapproval, the Association of Tennis Professionals (ATP) became one of the last major tennis governing bodies to implement rules for play in extreme heat, aligning with guidelines used by the Women’s Tennis Association (WTA) and at the Grand Slams. They now allow players a ten-minute cooling break if temperatures exceed 86 degrees and suspend play above 90 degrees, measured by the Wet-Bulb Globe Temperature (WBGT), a metric for heat stress in direct sunlight linked to temperature, humidity, wind speed, cloud cover and the angle of the sun.