The Bureau of Meteorology advised there will be a heatwave across a number of states from Thursday.
New South Wales, Victoria, Queensland, South Australia and Tasmania will all experience heatwave conditions, with the most severe heat predicted in central Western Australia.
It means, for three or more days in a row, daytime and night-time temperatures will be unusually high.
The bureau has forecast temperatures will rise 6C to 12C above average generally in NSW and the ACT, with the mercury tipped to reach a maximum of 14C to 16C above average on the coast and southern regions of the country.
“It’s as a result of a high pressure system moving into the Tasman Sea,” BOM meteorologist Jonathan How told SBS News.
While a cold front will bring relief to some southern parts of the country, which will drop back to the mid-20s over the weekend, the “heat will stick around” in central New South Wales, where the town of Bourke could hit up to 45C.
Canberra’s expected to record temperatures in the high 30s, while western Sydney should be prepared for intense heat in the low 40s. Melbourne will see temperatures of about 38C or 39C on Thursday and Friday, which should drop down to about 34C by the weekend.
It comes amid a cacophony of meteorological conditions in Australia over the past few months – ranging from tropical cyclones to thunderstorms.
A fortnight ago, authorities warned of "catastrophic" bushfire conditions during a similar heatwave as New South Wales sweltered through temperatures over 40 degrees.
“It’s not as intense as the last heatwave, but still very hot. We’re not likely to see any significant [temperature] records broken. There will be elevated fire dangers in South Australia and Western Australia on Thursday, which will spread into Victoria on Friday. There will likely be fire bans,” Mr How added.
In its annual climate statement, published on Tuesday, the Bureau of Meteorology outlined the country had its third-warmest year on record, with the annual national mean temperature 0.95 degrees above average.
It was amongst the 10 warmest years on record for Queensland, New South Wales, Victoria, Tasmania, and South Australia.
