A record-breaking heatwave is making its way across southeastern Australia, with temperatures set to exceed 40C in many parts of the country.
After Perth sweltered through three consecutive days above 40C at the weekend, Adelaide is now facing a four-day run that is expected to peak at 44C on Friday.
The extreme heat will reach the ACT, NSW and Victoria on Wednesday, with the Bureau of Meteorology expecting that inland parts of the territory and states will experience temperatures in the mid-to-high 40s.
In NSW, the heatwave will elevate fire risk as it moves through parts of the state still battling more than 100 bushfires on Thursday.
"We're looking at temperatures during the daytime that are around 10C-to-14C above average for this time of year,'' BOM acting NSW manager Jane Golding told reporters on Tuesday.
"With the heat comes fires so we're expecting some particularly tricky days for the fire response on Thursday, Friday, Saturday and Sunday."
The bureau expects temperatures in many locations to approach or even break December, and potentially, annual records.
Climatologist Dr Blair Trewin said Australia may this week hit a record for its warmest day, exceeding the 40.3C average maximum temperature set in January 2013.
Victoria could record its hottest December day on Friday if centres in the northwest such as Mildura and Swan Hill reach a forecast 47C.
"We're expecting a lot of December records to be challenged, particularly in northwest, north-central Victoria some parts of northwest Victoria may get very close to records for any time of the year," Dr Trewin said.
Mildura is forecast to swelter through three days in a row of 45C and above
"That's only happened once before in 1939 so it is certainly a very significant heatwave, particularly for December," he added.
In western NSW, temperatures are expected to climb above 45C while Canberra is bracing for 43C on Saturday.
"For the ACT we're looking at five days in a row above about 37 degrees. Three of those days will be in the low 40s, so severe to extreme heatwave conditions," Ms Golding said.
Alice Springs is expected to reach 45C on Thursday, close to its hottest temperature of 45.6C, a record met twice last summer.
Parts of Queensland are still sweltering despite a cool change bringing relief to Brisbane after it hit 41.2C on Monday, its highest December temperature since 1981.
But the western town of Birdsville is forecast to remain in the mid-40s all week, peaking at 47C on Wednesday.
As the mercury climbs, authorities are warning people to prepare for the hot weather.
"Extreme heat kills more Australians than any natural disaster and can affect anybody, but those most at risk are older people, young children and those with medical conditions," Victoria's State Response Controller Gavin Freeman said.
He advised people to stay hydrated, keep cool, never leave kids or pets in hot cars and check in on others who may be at risk.
Australian Associated Press