Soaring temperatures have sparked emergency-level bushfires on the first day of Australia's most intense heatwave in years.
South Australia, Victoria and parts of Tasmania are sweltering through oppressive temperatures as the mercury soars, the Bureau of Meteorology says.
The conditions may be the worst since the 2019-20 summer bushfires that killed more than 30 people and burned through millions of hectares.
Victorians steamed in the heat on Wednesday, with inland and northern parts reaching temperatures in the mid-40Cs and Melbourne also breaking 40C.
Emergency-level fires are burning out of control near Mount Lawson on the border between NSW and Victoria, with residents told to leave immediately before conditions become too dangerous.
More than 1000 hectares have been burnt and that is likely to grow over coming days, authorities warn.
Another out-of-control fire is burning at Longwood along the Hume Freeway in the state's north, with people being told to shelter inside as it is too late to leave.
There have been no reported injuries or structures damaged, but Victorian Emergency Management Commissioner Tim Wiebusch said there was potential for losses.
Total fire bans are in place for the Wimmera, South West and Central regions, including Melbourne and Geelong.
Mr Wiebusch said severe and extreme heat was being felt across the state, but the worst was yet to come with more intense conditions forecast on Friday.
"Victoria is one of the most fire-prone states in the world," he told reporters on Wednesday.
"We see conditions like this on a typical fire season, and certainly, Friday is one of those days that we've not seen for some time."
There will be slight reprieve for southern parts of the state on Thursday, but extreme fire dangers will persist in northern areas, Country Fire Authority chief executive Jason Heffernan said.
Forest Fire Management Victoria chief fire officer Chris Hardman warned suppressing fires during Friday's conditions will be impossible when the entire state is expected to face extreme fire danger.
"These are the days where we see lots of assets lost," he said.
Searing temperatures are set to continue across SA on Thursday after parts of the state sweltered through low-to-mid 40s, with Adelaide's maximum topping 42C and some inland and southeastern parts pushing 47C on Wednesday.
"Extreme heatwaves are likely to affect all Australians to some degree, not just those who are vulnerable, such as the elderly or those who are unwell, but healthy and active people as well," meteorologist Helen Reid said.
It was also a warm day for Tasmania with low to severe heatwaves building in the state's northeast.
The heat is expected to move into the ACT and NSW heading into the weekend, with the national capital to peak at 38C on Friday, while Sydney should reach 42C on the final heatwave day on Saturday.
The Royal Australian College of GPs is urging the public to prioritise hydration, rest indoors and check on people more susceptible to heat exhaustion and heat stroke.
Children and pets should never be left alone in cars, as the number of call-outs involving family members locked inside vehicles increased 26 per cent year-on-year, SA's Royal Automobile Association said.
Australia experienced its fourth-warmest year on record in 2025, while 2024 was the nation's second-warmest year.
