法国网球公开赛第一周出现的重大冷门（two）与因酷热条件而倒在球场上的人数一样多。周一一场首轮比赛中，一名球童几乎昏倒；周四，男子选手 Jakub Mensik 在一场五盘比赛后倒在 Roland Garros 的红土场上，称他的身体「just turned off」。由于「heat dome」，也就是一个持续存在、会困住暖空气并导致气温上升的高压区，气温一直徘徊在华氏 low- to mid-90s，或摄氏 low-30s。

湿球黑球温度「会考量环境条件的多个方面，例如温度、湿度、太阳辐射和风，」Rachel Cottle 说。湿球黑球温度达到 86 degrees Fahrenheit（30 degrees Celsius）代表人类健康危险区的开始。Cottle 进行的研究显示，即使是健康的年轻人，当湿球温度达到约 88 degrees Fahrenheit（31 degrees Celsius）时，也会开始出现问题。

据报导，French Tennis Federation 在 Roland Garros 球场备有 two 支可测量湿球黑球温度的温度计，并已制定计划：如果温度超过某个门槛，就在盘与盘之间延长休息时间，甚至取消比赛。2017 年发表的研究发现，today’s 湿球黑球温度可能会在 20 年内成为北半球地点的常态。长时间暴露在 95 degrees Fahrenheit（35 degrees Celsius）的湿球温度下，是人类能够存活的上限，因为汗水基本上会停止蒸发。

The first week of the French Open has yielded as many major upsets (two) as people collapsing on the court due to sweltering conditions. A ball girl nearly fainted during a first round match on Monday, while men’s player Jakub Mensik keeled over on Roland Garros’ red clay on Thursday after a five-set match, saying his body “just turned off.” Temperatures have hovered in the low- to mid-90s Fahrenheit, or low-30s Celsius, due to a “heat dome,” a persistent area of high pressure that traps warm air and causes temperatures to rise.

Wet bulb globe temperature “takes into account multiple aspects of the environmental conditions such as temperature, humidity, solar radiation, and wind,” says Rachel Cottle. A wet bulb globe temperature of 86 degrees Fahrenheit (30 degrees Celsius) represents the start of the danger zone for human health. Cottle has conducted research showing that even healthy young people start to experience issues when the wet bulb temperature reaches around 88 degrees Fahrenheit (31 degrees Celsius).

The French Tennis Federation reportedly keeps two thermometers that can measure the wet bulb globe temperature on courts at Roland Garros, with plans in place to have extended breaks between sets or even cancel matches if they surpass a certain threshold. Research published in 2017 found that today’s wet bulb globe temperatures are likely to be the norm within 20 years for locations in the northern hemisphere. Prolonged exposure to wet bulb temperatures of 95 degrees Fahrenheit (35 degrees Celsius) is the upper limit of what humans can survive, as sweat essentially stops evaporating.