Sydney and Melbourne could have to endure 50C summer days by the turn of the century, as global warming gets worse.
A new study from the Australian National University in Canberra analysed Bureau of Meteorology data from the country's two biggest cities.
Researchers say sweltering summers are inevitable.
"We have to be thinking now about how we can be prepared for large population groups commuting to and from the CBD on these extremely hot days, how we send young children to school on 50C days, how our hospitals are prepared for a larger number of admissions of young or old people, and how our infrastructure can cope with it," ANU climate scientist Dr Sophie Lewis told the ABC.
"We've already seen an increase in excess heat deaths in heatwaves in 2009, due to those extreme heatwaves, and that's likely to occur even more under these 50C days."
The ANU study only analysed Bureau of Meteorology data from Sydney and Melbourne, but Dr Lewis said all of Australia could expect to see hotter extremes in the future, the ABC reported.
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