The Extreme Heat Policy is a rule pertaining to the Australian Open (tennis). It was introduced in 1998 after consultation with a number of tennis players. Its current iteration was first implemented in 2019 and uses a scale of 1 to 5 that accounts for the physiological variances between adults, wheelchair and junior athletes while also taking into account the four climate factors – air temperature, radiant heat or the strength of the sun, humidity and wind speed – which affect a player’s ability to disperse heat from their body.