Millions of Australians are set to swelter through blistering heatwave conditions over the long weekend, putting authorities on high alert.
Temperatures are soaring across southeastern parts of the country today, with the mercury heading for 40 degrees in Sydney, Brisbane and Adelaide.
Temperatures in Adelaide will soar to 37 degrees today and soar to 45 tomorrow, while inland parts of SA could reach 48 degrees.
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Annual Adelaide Australia Day event The Aus Lights on the River and the evening fireworks have been cancelled because of the heat. Usually around 25,000 spectators take in the annual event.
Brisbane will hit a high of 35 today before creeping up to 37 degrees for Australia Day.
Canberra is forecast to nudge 40 degrees this afternoon - the hottest in the country today.
Fire authorities in Victoria are asking residents across the state ot heed emergency service warnings, as extreme-to-severe heatwave conditions cause bushfires in the landscape to flare.
"We have not seen severe to extreme intensity heat wave conditions like we are going to experience over the next seven days since 2009," Emergency Management Commissioner Tim Wiebusch said.
"Take heed of the warnings, look after yourself, look after your family, those that are vulnerable."
Emergency services were forced to issue an urgent reminder not to leave children, pets or older people unattended in vehicles after paramedics responded to 11 cases of children locked in hot cars across Melbourne and regional Victoria.
"The temperature inside a vehicle can double and become deadly within minutes," Ambulance Victoria Director of Emergency Management Dale Armstrong said.
"It is particularly dangerous for children to be left inside vehicles, as a child's body temperature rises three to five times faster than an adult."
The mercury surpassed 38 degrees in Melbourne yesterday, while temperatures soared beyond 46 degrees in parts of northern Victoria.
The city is headed for a top of 43 degrees on Tuesday, while northern parts of the state could hit record-breaking highs of 48 degrees.
"If you are on the coast you will see a bit of relief coming through on Tuesday, but that does mean we are expecting some very hot days on the way," Bureau of Meteorology's Jonathan How said.
"Anywhere inland, unfortunately relief only comes at the end of the week, even into next weekend, so we are looking at a run of five to seven days above 40 degrees and some locations even above 45 degrees, even pushing towards 50 degrees."
While Australians on the east coast prepare to sweat through the week, those in the west are dealing with the impact of a second tropical cyclone in a matter of weeks.
Tropical Cyclone Luana made landfall as a Category 2 system when it made landfall along the Dampier Peninsula north of Broome.
Wind gusts up to 106km/h were recorded north of Broome, in Lombadina, along with more than 100 millimetres of rain since midnight yesterday.
The storm has since weakened to a category 1 system moving inland.
Residents along the Kimberley coast should expect heavy rainfall and damaging winds over the long weekend, which is only expected to ease from Tuesday.