The Australian Open is a mid-summer event in Melbourne and will always have days of scorching temperatures of 40 degrees Celsius and over.

The tournament's extreme heat policy calls for the roofs to be closed on the main show courts and play to be suspended on outer courts when the temperature reaches 40 degrees Celsius (104 Fahrenheit) and the wet-bulb globe temperature (WBGT), which takes into account humidity and wind speed, reaches 32.5 Celsius (90.5 Fahrenheit).

The high temperature Friday marginally reached 40 degrees Celsius, but the wet-bulb temperature remained below the 32.5 Celsius threshold, so play was not halted.

Click on the links for more stories:

http://www.abc.net.au/news/2018-01-19/australian-open-heat-policy-federer-djokovic-monfils/9342328

http://abcnews.go.com/Sports/wireStory/players-turn-heat-australian-open-weather-policy-52457132