Heatwave warnings are in place for every mainland state and territory, with some capital cities approaching 40 degrees this long weekend.
Canberra is forecast to reach 39 degrees, Adelaide 37 degrees and Brisbane 35 degrees on Sunday.
The Bureau of Meteorology (BoM) has forecast potentially catastrophic bushfire danger as an intense and long-lasting heatwave drags across NSW, South Australia, Victoria and southern Queensland.
These states, along with the ACT and Northern Australia, are experiencing low to severe heatwave warnings, with a maximum danger in place across the desert where the WA and SA borders meet.
Meanwhile, six active major fires in Victoria could continue to burn for days or even weeks, according to the State Control Centre.
The organisation said that over 20 fires linked to campsites and bonfires were started on Saturday, despite a statewide total fire ban.
And a cyclone is threatening homes and infrastructure on the other side of the country, with communities in Northern WA bracing for flooding.
Heatwave warnings
While there are more severe heatwave warnings in place than extreme warnings, authorities say everyone in these areas could be at risk of the heat.
In NSW, an extreme heatwave warning is in place for the Snowy Mountains and South West Slopes, with the BoM saying that heatwave conditions across the state are "expected to intensify this weekend and early next week".
Parts of North East Victoria are also at the extreme warning level, where the BoM is forecasting that maximum temperatures could reach the mid-forties.
In South Australia, there is an extreme heatwave warning for Flinders.
The rest of mainland Australia is experiencing a less intense heatwave warning level, while Tasmania is the only jurisdiction without a heatwave risk as of Sunday morning.
The BoM recommends seeking a cool location, whether that’s at home, a community centre or a library, to escape the heat and reduce your risk of dehydration and heat exposure.
Victorian fires
Hot to very hot temperatures in Victoria, combined with "dynamic conditions", could lead to major fires burning for weeks to come, according to a Victorian State Control Centre spokesperson on Sunday morning.
They confirmed that a fire in Longwood has now grown to around 133,000 hectares in size, and a second in Walwa is about 121,000 hectares in size.
Over 900 firefighters and almost 200 fire vehicles have been at the scene of those two fires this long weekend.
The spokesperson told SBS News that people should reconsider their need to be outdoors in proximity to the fires, and follow the total fire bans in place.
"Disappointingly yesterday, during a statewide total fire ban, more than 20 fires that started were from campfires, bonfires and burn-offs," they said.
"It is extremely important that people do not light any fires during a Total Fire Ban."
They also urged the public to obey roadblocks and follow directions and authorities.
Flooding risk in WA
Residents of Western Australia’s north coast are facing damaging wind gusts and heavy rainfall as Tropical Cyclone Luana moves inland.
The category one system is packing winds of up to 110 k/ph and could cause flash flooding in the northwest Kimberley district, the BoM said.
The area between Broome and Cockatoo Island, including Derby, was expected to bear the brunt of the cyclone.
Luana is likely to weaken below tropical cyclone strength on Sunday morning as it moves further south inland.
"Tides will be higher than normal between Beagle Bay and Kuri Bay and large waves may produce minor flooding of low-lying coastal areas," the BoM said.
A Cyclone Watch and Act was issued for an area from Coulomb Point Nature Reserve to Cape Leveque, with residents and visitors told to shelter indoors.
BoM forecaster Jonathan How said heavy rain leading to flash flooding was possible.
"This may cause roads to become flooded and communities to be isolated."
Additional reporting by the Australian Associated Press.
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