Residents in South Australia, Victoria and Queensland are bracing for another day of record-breaking heat.
Adelaide is forecast to hit 45C on Thursday, and the Bureau of Meteorology says the city's 80-year-old record high of 46.1C is within reach.
"You wouldn't rule it out," forecaster Jonathan Fischer said.
The heat will intensify in the state's regional centres, with a high of 49C expected at Port Augusta, and 47C at Port Pirie and Roxby Downs.
"Nowhere is going to escape," Mr Fischer said.
"We will see records broken tomorrow, with many locations forecast to be near their maximum all-time record."
Residents living in the outback town of Birdsville endured 10 consecutive days of 45C and above until Monday, exceeding the previous six-day run that occurred in the same town in 2004 and 2013.
Bureau of Meteorology forecaster Mark Trenorden said the Australian record of 13 days occurred in Marree in South Australia in January 1973.
"This is the longest spell of 45 ever in Queensland," he told AAP.
State weather records have also fallen in Cloncurry and Camooweal, where the mercury has hit 40 degrees or above for the past 39 days, with no reprieve in sight.
'Oppressive' nights
Victorians are also being warned to prepare for hot conditions and an "oppressive" night as the mercury begins its climb into the 40s.
The city is forecast to reach 36C on Thursday, while low 40s are forecast for other parts of the state.
Melbourne will swelter through its hottest night in a year with the temperature dropping to just 29C, before hitting a top of 43C on Friday.
"The overnight minimum temperatures are nothing short of oppressive unfortunately," the Bureau of Meteorology's Richard Russell said.
Authorities are asking people not to take risks during the hot weather, including leaving children in cars or swimming at unpatrolled beaches.
"Let's take something from these drowning deaths. Twenty people have lost their lives, that's 20 families and friends of those people that have been impacted," Emergency Management Commissioner Andrew Crisp said.
A cool change is expected late on Friday, but it will bring wind gusts of up to 80km/h, thunderstorms and an increased fire risk.
Fire crews are on stand-by while extra paramedics and ambulances will be on call to assist those struggling in the heat, Mr Crisp added.
