One early candidate for a 50-degree day was Thargomindah, a remote Queensland town 1000 kilometres west of Brisbane. Its temperature jumped to a peak of 48.5 after a blast of heat saw it add 2 degrees in half hour, according to the Bureau of Meteorology.

"It's got a few days to go, for sure," Neil Plummer, the bureau's assistant director of climate services, said. "Things will get warm again out in the west and centre, and by around Thursday that hot air will be extending into the south-east."

Australia has posted nine days of average maximum temperatures above 39 degrees in 2013. Seven of the 20 hottest days by average maximum have been registered just this month. A delayed northern monsoon means there is less moisture and cloud cover over the continent, leaving a huge inland area to bake for most of the past two weeks.

"The last four months of 2012 were the warmest on record and that's extending into January," Mr Plummer said.

Drier-than-usual conditions over much of the country, combined with the current heat and a big build-up in fuel load, has created severe fire hazards over large parts of south-eastern Australia.