What is the Wimbledon heat rule? Has it been used? Explaining temperature threshold and when 10-minute breaks are introduced

Wimbledon is up and running, and this year’s cohort of elite players are having to contend with more than just their world-class opponents in SW19.

The weather created significant challenges during the matches on Monday, and it looks set to be more of the same on Tuesday, with temperatures reportedly set to exceed 30°C.

Monday set the record for the hottest opening day since records began at the iconic Grand Slam, with temperatures reportedly reaching 32.3°C.

However, it failed to top the scorching summer heat seen in 2015, when temperatures reached as high as 35.7°C, the hottest day in the history of Wimbledon.

It was also not hot enough to force the organisers to enforce the heat rule used at the Championships.

The heat rule at Wimbledon can be brought in during any of the singles matches across the men’s, women’s, boys, girls, wheelchair and quad wheelchair tournaments.

The rule comes into place when the Wet Bulb Globe Temperature (WBGT) hits or exceeds 30.1°C.

The WBGT is not a measure of the temperature, but in fact a measure of the heat stress while in direct sunlight, taking into account air temperature, humidity and the surface temperature.

The WBGT is checked 30 minutes before the start of play, and again at 14:00 and 17:00.

The rule can be brought in after a match has started, and it can be implemented by either player if they request it.

The rule means that players can have a 10-minute break after the second set during the best-of-three-set matches or after the third set during the best-of-five encounters.

During the 10-minute break, players are not allowed to receive advice, medical assistance or coaching, but they may leave the court if they wish.

If the rule is brought in, but the temperature drops during the contest, it will remain in place for the rest of the match.

The heat rule is yet to be brought in at Wimbledon 2025. The temperature may have exceeded 30.1°C on Monday, but not in the eyes of the WBGT.

The use of other factors to measure heat stress meant that players had to rely on ice packs, cold towels and water to regulate their temperature.