Wimbledon 2025 is kicking off under blazing sunshine, with temperatures expected to reach record highs. On Monday, the air temperature at the All England Club could hit 33°C or even 34°C, which could make it the hottest opening day in Wimbledon history. The previous record was 29.3°C, set back in 2001.

When you add in humidity, the heat could feel more like 37°C for players and fans. The hot conditions are expected to continue into Tuesday, raising concerns about how the weather will affect matches and player health.

To protect players, Wimbledon has a heat rule that kicks in when conditions get too intense. The rule is based on something called the Wet Bulb Globe Temperature (WBGT)—a measure that combines air temperature, humidity, and surface heat to determine how hot it actually feels on court. If the WBGT reading hits 30.1°C or more, players are allowed to take a 10-minute break during their matches.

Wimbledon: When is the heat rule enforced? 

The rule applies to all singles matches, even if they’ve already started. For best-of-three-set matches (like women’s and junior matches), the break happens after the second set. 

For best-of-five-set matches (men’s singles), it comes after the third set. Only one player needs to ask for the break for it to be granted. During the break, players can leave the court to cool down, but they’re not allowed coaching or medical treatment.

Officials check the WBGT reading three times a day: 30 minutes before matches start, at 2:00 p.m., and again at 5:00 p.m. If the rule is in effect when a match begins, it stays in place until that match finishes—even if temperatures cool down later.

When does the rule not apply?

The heat rule does not apply to matches played under a roof—like those on Centre Court or No.1 Court—since those indoor conditions are more controlled and less risky.

There are also limits to how the rule is used for matches that stretch over two days. For example, if a three-set match finishes one set before being paused overnight, the rule doesn’t apply the next day.

With high temperatures forecast through Tuesday, expect Wimbledon’s heat rule to be a major factor in this year’s early matches.