Even for a sport that spends most of the year chasing the sun around the globe, the heat and humidity tennis players will face during the Tokyo 2020 Olympic Tennis Event is expected to rank among the most extreme conditions they will experience on tour in 2021.

For that reason, the ITF has in place an Extreme Weather Policy, which introduces measures to protect the players when the on-court conditions become challenging, and in some instances unplayable.

The Extreme Weather Policy was activated on Day 1 of the Olympic Tennis Event, and will be in effect for all matches on Day 2 while the conditions remain above the heat and humidity thresholds on site - more on that later. In addition, breaks at change of ends and after sets have been extended by 30 seconds for all matches from Day 2 onwards, to offer a little more respite. 

So how is the Extreme Weather Policy monitored and implemented, and what happens when it comes into effect? Read on…

What is ‘extreme weather’?

For the most-part – but not exclusively – extreme weather refers to the heat and humidity players are facing on court.

To monitor this, the tournament referee refers to the Wet Bulb Globe Temperature, a measure of heat stress in direct sunlight which also takes into account wind speed, cloud cover and the angle of the sun.

The West Bulb Globe Temperature (WBGT) is measured in Celsius or Farenheit – the ITF delivers its monitoring reports in Celsius. WBGT temperatures are taken each day, every 30 minutes during the Olympic Tennis Event, starting at 10:00am local time.

Once the WBGT threshold reaches 30.1°C, the Extreme Weather Policy comes into effect.

What happens next?

There are two options available to the tournament referee once the Extreme Weather Policy comes into effect. The first is modification of play, implemented at 30.1°C. Chair umpires are instructed to inform the players so that they are aware the policy is active, whether before or during the match – for those on court, this happens at a change of ends.

‘Modification of Play’ introduces a 10-minute break between the second and third sets of singles matches at the request of either player – if neither player wants to take a break, the match may continue. Doubles matches, which are settled with a match tiebreak at one set all, do not feature a 10-minute break.

Should the Extreme Weather Policy be lifted while players are on court, any matches currently in play will continue to implement the policy until completed.

What is allowed during the 10-minute break?

Players may leave the court for up to 10 minutes after the second set, returning to be ready to begin the third. The chair umpire will call time after nine minutes, 30 seconds to indicate that players should be ready to resume play shortly afterwards. If a player does not return to court, they will be subject to time violations – whether serving or receiving.

While off-court, players can:

• Go to the bathroom
• Take a shower
• Change their outfit
• Have something to eat or drink
• Adjust any medical straps or get retaped

However, they cannot:

• Receive a medical evaluation, take a medical time-out or receive any treatment unless approved by the tournament referee or supervisor
• Talk with their coach, or receive any coaching
• Use electronic devices
• Take a further break to go to the bathroom or change their outfit, extending the 10-minute break

What if the WBGT continues to rise?

Once the Wet Bulb Globe Temperature hits 30.1°C, an internal advisory group will be convened within 90 minutes to begin planning for the second option avalible via the Extreme Weather Policy: suspension of play.

The group includes the tournament referee, representatives from the tournament medical services, and administrative staff.

There are many factors to consider when weighing up the decision to suspend play, including:

• The weather forecast for the previous two days, to factor in the heat players have already been dealing with; and for the next two days, considering what they can expect to face as the tournament progresses
• Any anecdotal points raised by tournament medics about the conditions

As a guideline, a WBGT of 32.2°C is considered a second inflection point for convening and reaching a decision, but this is not a rule.

What happens once play is suspended?

If the tournament referee decides to suspend play at the Ariake Tennis Park in line with the Extreme Weather Policy, any matches in progress on the outside courts will be suspended once an even number of games have been played in the current set. If the players are involved in a tiebreak, the match will be suspended once it is completed.

The Ariake Tennis Park has a retractable roof and climate control, which allows play to continue with the roof closed. Like the action on the outside courts, any match in progress will be temporarily suspended after an even number of games in the set, or after a tiebreak, following which the roof will be closed – and will stay closed for the remainder of the match.

Why not start play later, when it may be cooler?

There are many factors to consider when scheduling a tennis event. For instance, anyone who follows the sport knows how susceptible outdoor tournaments are to the elements - rain, specifically, which is a potential factor in Tokyo.

Then there is the matter of time. Some matches on Day 1 at the Games lasted less than an hour, while others broke the three-hour mark, so an early start time presents the best chance of completing all of the day's matches. And tennis is part of a multi-sport schedule at the Olympic Games, with five medal events taking place over nine days. 

Scheduling will always be problematic when dealing with extreme conditions, but decisions are ultimately made to protect player health and welfare.

Why is it called the Extreme Weather Policy, and not the Extreme Heat Policy?

Because there’s other weather out there! Another potential factor in Tokyo will be thunderstorms and the possibility of lightning strikes, which would also result in the suspension of play until the likelihood of a lightning strike has passed.