French Open Players Face Heat as Wet Bulb Globe Temperatures Rise

Two players collapsed during the first week of the French Open, matching the number of major upsets recorded in the same period. A ball girl nearly fainted on Monday, and men's player Jakub Mensik fell to the clay after a five-set match on Thursday.

Temperatures in Paris have reached the low- to mid-90s Fahrenheit during a heat dome that traps warm air over the region. The French Tennis Federation maintains two thermometers that record wet bulb globe temperature at Roland Garros.

The wet bulb globe temperature incorporates air temperature, humidity, solar radiation, and wind speed. Rachel Cottle, a postdoctoral research fellow at Texas Health Presbyterian Hospital Dallas, said the metric evaluates multiple environmental factors that affect heat-related illness risk.

A reading of 86 degrees Fahrenheit marks the start of the danger zone because sweat evaporates less efficiently. Research by Cottle indicates healthy young adults begin to experience issues near 88 degrees Fahrenheit.

Players have used shade and ice packs between games to lower body temperature. Health researcher Kat Fisher noted that fit athletes sweat earlier and more efficiently than non-athletes, raising their heat tolerance. The French Tennis Federation has contingency plans for extended breaks or match cancellations if wet bulb globe readings exceed set thresholds.

The other three Grand Slam tournaments maintain similar heat policies based on the same measurement. Research published in 2017 projected that current wet bulb globe temperatures will become typical across the northern hemisphere within 20 years. A later global analysis identified northern India, China, northern Australia, Africa, Central America, and Southeast Asia as regions facing disproportionate increases.