Australian Open develops new extreme heat policy

Officials have scrapped the use of wet bulb globe temperature readings for next month's Australian Open which should result in more matches suspended or delayed by Melbourne's notoriously hot, dry and often windy conditions in January.

The wet bulb index is a measure of the heat stress in direct sunlight, which takes into account temperature, humidity, wind speed, sun angle and cloud cover.

Australian Open officials said Saturday a newly developed "heat stress scale," which takes into account air temperature, radiant heat, humidity and wind speed, will instead be applied along with more comprehensive measuring of conditions across Melbourne Park.

A 10-minute break between the third and fourth set will also be introduced in men's singles matches when the five-point scale nears its most extreme point.

The introduction of heat-related breaks for male players brings the tournament into line with the U.S. Open which was repeatedly forced to stop play earlier this year.

Play will be suspended on outdoor courts and the roof closed on the marquee courts when the heat scale reading is 5.0 or above.

The Australian Open begins on Jan. 14.