Temperatures at the French Open are set to rise over the coming days having already hit uncomfortable levels for everyone involved at Roland Garros, but cooler weather is expected next week.
The latest Paris forecasts, which include yellow warnings for extreme high temperatures from Wednesday to Friday, might lead to mandatory extra breaks for players if the so-called Wet Bulb Globe Temperature (WBGT) exceeds the 32.2 degrees Celsius specified in the rules.
The WBGT is used to determine heat stress on the human body, with factors such as humidity, solar radiation and wind taken into account.
But heat measures were not triggered in the first three days of the clay grand slam despite conditions described as "roasting" by Germany's Laura Siegemund.
Andrey Rublev's first-round match against Ignacio Buse had to be briefly interrupted because a ball girl was unsteady on her feet and almost fainted.
Meanwhile, Canadian Gabriel Diallo retired in the first round because of the extreme heat.
The strong sunshine is also a problem when players try to serve while looking up. Several have taken to wearing sunglasses.
German tennis icon Boris Becker said the only silver lining was that the heat risk is now taken more seriously in tennis.
"You can't explain to any young player today how we used to be treated back then," Becker, who won six grand slam titles between 1985 and 1996, told Eurosport.
"God help you if you complained back then, then you were nothing other than a wimp. I think it's good that it's different today and the players are protected."
Spectators are also struggling and most have tried to seek out shady spots on the Roland Garros grounds. There have also been long queues in front of the water dispensers and sunscreen stands.
Relief is not expected until Sunday, when temperatures are set to fall to 24 degrees.
