Temperatures in Sydney hit their highest level on record on Friday, with the mercury in Australia's biggest city reaching 45.8 degrees Celsius (114.4 Fahrenheit) in the mid-afternoon.
Sydney's previous hottest recorded temperature was 45.3 degrees set in 1939.
"It's a historic day for Sydney today," Weather Channel meteorologist Dick Whitaker said.
"We haven't seen a day like this in Sydney's recorded history."
It is the latest record to fall as Australia swelters under a heatwave that has affected some 70 percent of the vast country and has created what some experts have called a "dome of heat" over the nation's outback centre.
The extreme weather, which has exacerbated bushfires, last week saw the government's weather bureau upgrade its temperature scale by introducing new colours to cover projected forecast highs.
At one point last week, central Australia was shown with a purple area on the bureau's forecast map, a new colour code suggesting temperatures were set to soar above 50 degrees (122 Fahrenheit).
The new scale also features a pink code for even higher temperatures.
Australia's all-time record temperature is 50.7 degrees, set in January 1960 at Oodnadatta in South Australia state.
The record weather comes as firefighters battle blazes in New South Wales and Victoria, and almost two weeks after a dangerous fire in the southern island state of Tasmania razed more than 100 homes.
Prime Minister Julia Gillard, at commemorations for bushfires in Canberra that killed four people and destroyed close to 500 homes in the national capital a decade ago, urged people to take precautions.
"Everyone should ensure they take the appropriate precautions to stay safe and monitor information from local emergency services as they work to protect lives and property," she said.
Bushfires are a common feature of the Australian summer, and climate experts have said that they may become more intense due to global warming.
In 2009, the so-called Black Saturday firestorm destroyed more than 2,000 homes and killed 173 people in Australia's deadliest natural disaster of modern times.