Wimbledon’s ‘heat rule’ explained as Pippa Middleton spotted breaking major Royal Box protocol - but for good reason
Pippa Middleton turned plenty of heads at Wimbledon this week, but it wasn't just because of her floral summer dress.
The younger sister of Kate Middleton was spotted in the Royal Box alongside her mum, Carole Middleton, on Monday (6 July), wearing a wide-brimmed hat that technically goes against one of the tournament's long-standing etiquette rules.
Royal Box guests are usually expected to stick to a fairly strict dress code, with the Wimbledon website stating that while men are expected to wear suits, jackets and ties, women are asked not to wear hats because 'they tend to obscure the vision of those seated behind them'.
It's a rule that's been in place for years, but with temperatures soaring across the Championships this week, there may have been a very good reason for Pippa's fashion choice.
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Photos from the day show that she removed the hat at various points during play, suggesting she was balancing sun protection with Royal Box etiquette as the heat intensified.
And with Wimbledon facing some of its hottest conditions of the tournament so far, officials are already keeping a close eye on temperatures.
The All England Club operates an Extreme Heat Policy, or 'heat rule', designed to protect players when conditions become too demanding.
Rather than relying on the air temperature alone, officials use something called the Heat Stress Index, which is measured using the Wet Bulb Globe Temperature (WBGT).
This takes into account air temperature, humidity, wind speed and the heat radiating from the grass courts.
Measurements are taken 30 minutes before play begins, then again at 2 pm and 5 pm throughout the day.
If the Heat Stress Index reaches or exceeds 30.1°C, players competing in singles matches are allowed to request a heat break.
Only one player needs to ask for it, but both competitors receive the break.
Women's singles players can take a 10-minute break between the second and third sets, while men's singles players are allowed the same length of break between the third and fourth sets. Wheelchair events receive a 15-minute break instead.
During that time, players can leave the court, use the facilities, take a shower or change their clothing, but they cannot receive medical treatment or tactical coaching.
The policy also comes with a few exceptions.
It doesn't apply to matches played under a closed roof on Centre Court or No. 1 Court, where conditions are far more controlled. Doubles matches are also excluded, as they are considered less physically demanding than singles.
If conditions become even more extreme and the Heat Stress Index climbs above 32.2°C, tournament officials can suspend play entirely on outdoor courts until it is safe to continue.
While the heat rule applies to players, Wimbledon has also shown flexibility with spectators during particularly hot weather.
That could explain why Pippa's hat didn't cause any issues despite the usual Royal Box guidance.
Wimbledon’s strangest rules
Wimbledon has strict rules and regulations for pretty much everything - from the length of the grass to the temperature of the tennis balls, and you can be fined thousands of pounds for certain conduct violations.
Curfew
While at other grand slams, play continues late into the night, at Wimbledon there’s a strict 11pm curfew.
This means tennis fans sometimes have to go to bed on a cliffhanger.
Novak Djokovic and Rafael Nadal’s 2018 semi-final clash was suspended after the third set. Meanwhile, Andy Murray was particularly peeved when he was in the lead against Stefanos Tsitsipas in 2023, but went on to lose when the game was paused overnight and restarted the following morning.
Timed toilet breaks
Players are limited to one toilet break for matches up to three sets, and two if it goes on for longer.
They can only go during a set change and they have to be back within three minutes, or they risk giving a point to their opponent.
The longest ever Wimbledon match lasted a whopping 11 hours over three days, so players better get their nervous wees in before the match.
Temper tantrums
Players can be fined up to £36,900 for smashing their rackets. Djokovic is believed to have smashed over 60 of them over the course of his career.
Bad language can also result in the same maximum fine.
Countdown to serve
As soon as the ball goes out of play, the serving player has just 25 seconds to hit their serve, or the umpire can call a violation which could potentially grant a point to their opponent.
Fines for not trying hard enough
Players must demonstrate they’re giving their all to win the match. Australian player Bernard Tomic was fined an eye-watering £45,000 after he was accused of not putting in enough effort to beat French player Jo-Wilfried Tsonga, losing after just 58 minutes.
Age limits
Players have to be at least 14 to compete, which means youth sensations like Coco Gauff were initially barred from taking part.
Spectators, meanwhile, have to be accompanied by a guardian if they’re under 16. Under-fives aren’t permitted at all onto show courts.
This meant Serena Williams' two-year-old daughter Adira River couldn't watch her mum's comeback at this year's grand slam, while not all of Andy Murray's four children could watch his final doubles appearance in 2024.
The grass and the balls
Everything at Wimbledon is just so. The grass is cut to 8mm, which is apparently best suited for modern tennis play and for the grass to survive.
Meanwhile, the tennis balls are kept in a fridge in order to maintain a constant temperature of 20°C. A consistent temperature is important because it apparently affects the way the balls bounce. The more you know.
Tennis whites
It was originally just female players who were required to wear all-white on the court. According to Tennis Fashions: Over 125 Years of Costume Change, the rule was introduced because it was ‘quite unthinkable that a lady should be seen to perspire’. OK then…
Eventually, the rule was imposed on men too.
A single trim of colour is allowed around the neckline and sleeve cuffs, but this must be no thicker than 1cm.
In 2022, an exception was made so women could wear dark undershorts to feel more comfortable if they were on their periods.
Topics: Wimbledon, Royal Family, Weather, UK News, Celebrity
Rhiannon Ingle