What to know about the heat policy at the Australian Open

MELBOURNE, Australia — The Australian Open put its Extreme Heat Protocol into play on Tuesday for the second time in this tournament.

The policy uses a ‘Heat Stress Scale’ ranging from 1 to 5 and takes into account the air temperature, radiant heat, humidity and wind speed.

When the index hits 5, play is suspended on outside courts and the roof is closed on the three arenas at Melbourne Park.

That happened on Saturday during Jannik Sinner’s match on the center court, and the two-time champion felt he was lucky with the timing. Organizers said it was the first time since 2023.

The roof was open to start Day 10 but the measures were imposed again after Aryna Sabalenka beat Iva Jovic 6-3, 6-0. It was then closed for the next match, Alexander Zverev's 6-3, 6-7 (5), 6-1, 7-6 (3) win over 20-year-old Learner Tien.

“At the end of the match, it was really hot out there,” Sabalenka said. “I’m glad they closed the roof kind of, like, almost halfway so we had a lot of shade in the back so we could go back and stay in the shade."

“I guess, yeah, as a woman,” she added, laughing, “we are stronger than the guys, so they had to close the roof for the guys so they don’t suffer!”

The heat

The protocol aims to ensure player safety and consistency during extreme conditions. With temperatures forecast to reach 45 degrees Celsius (113 Fahrenheit) late Tuesday, organizers were prepared.

The temperature didn't quite reach predictions — at least not at the Australian Open site near downtown Melbourne — peaking at just over 42 Celsius (108 F) at 5 p.m. local time. The roof was opened for Carlos Alcaraz's 7-5, 6-2, 6-1 quarterfinal win over Australia's Alex de Minaur, the last match of the day.

The heat scale

Here’s what to know about the Australian Open’s Extreme Heat Protocol:

The Australian Open introduced the Heat Stress Scale in 2019, a measure from 1 to 5 that takes into account four climate factors: air temperature, radiant heat, humidity and wind speed.

It was developed to provide consistency for all players and minimize the risk of heat-related illness.

It sets thresholds for cooling interventions. In the event of extreme heat, the tournament referee has the authority to suspend play or order extra cooling breaks.

Play is automatically suspended when the index hits 5 in women’s and men’s singles.

The referee may suspend the calling of any upcoming matches on outdoor courts. And if matches on the outdoor courts have been suspended, the referee may make the decision to close the roof — or to keep the roof closed — for any upcoming matches on the arena courts.

The referee will make the decision as to when to call for the resumption of play, and each player must be given at least a half-hour of notice prior to the resumption of play.

When the index reaches 4, organizers can impose an extra 10-minute break between the second and third sets in women’s singles and between the third and fourth sets in men’s singles.

In an arena stadium, if the roof is closed before the end of the first set in a women’s singles match or before the end of the second set in a men’s singles match, there will be no extra cooling breaks.

“Crazy heat”

“I knew . . . that they won’t let us play in crazy heat," Sabalenka said. "If it would reach the 5, they would definitely close the roof, so I knew they were protecting us, our health. Yeah, anyway, when we’re finished ... it was 4.4, so it was quite hot.”

Forecast for Wednesday

The maximum temperature is forecast to drop to 24 Celsius (75 F) on Wednesday. Apart from a high of 31 (85 F) on Friday, the maximums for the remainder of the week are forecast to stay in the 20s (Celsius), which is mild by Melbourne standards in summer.

The women's final is scheduled for Saturday and the men's final is Sunday.

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