Many people are heading to the beach to cool down
Residents of south-eastern Australia are being warned to expect the worst heatwave in a century.
Emergency services are on high alert and, in the state of Victoria, locals are being urged to prepare bush fire plans in case they need to flee.
Temperatures went up to 45.5C (114F) in Adelaide, its hottest day in 70 years.
In Melbourne, two people died in the searing heat, including a 75-year-old man who collapsed while walking to his car, the AFP news agency said.
'Extreme heat policy'
Some train and tram services were cancelled as rail lines buckled in the heat. There were also power outages, as people turned on their air-conditioning units to cool down.
The heat wave in Victoria is expected to last several days and be the region's worst since 1908, according to AFP. The average temperature in Melbourne at this time of year is 25.8C (78F).
Spectators have also been feeling the heat at the Australian Open
Play at the Australian Open tennis tournament in Melbourne was interrupted as temperatures reached 41C (106F) and organisers for the first time enacted their "extreme heat policy".
The women's singles quarter-final between Serena Williams and Svetlana Kuznetsova was halted for about 45 minutes as the roof on the Rod Laver Arena was closed, allowing the temperature on court to be lowered.
Williams said: "I was in like an out-of-body experience. I kept trying to tell myself that it's not hot, you know... But it got hotter."
Meanwhile in the state of South Australia, officials cancelled a horse race meeting in the town of Gawler because of the extreme weather conditions.