Thousands of people in 28 communities are being urged to evacuate a large fire zone as an out-of-control blaze bears down on them in Victoria.
An emergency warning has been issued for the communities west of Ballarat with concerns about a wind change expected to sweep the area between 6pm and 7.30pm.
Residents in another nine townships nearby have also been advised to leave.
Conditions are not expected to ease until about midnight, Victorian Country Fire Authority chief officer Jason Heffernan told reporters on Thursday afternoon.
He said 1000 firefighters were attempting to control the fire at Bayindeen-Rocky Road that ignited in bushland and "rapidly took off".
No properties had yet been reported as damaged.
"I'm here to tell communities the fire situation will get worse before it gets better," Mr Heffernan said.
The Western Highway was closed in both directions between Ballarat and Ararat, with diversions set up using the Sunraysia Highway and Pyrenees Highway via Avoca.
People in the fire area have been urged to head east towards Ballarat, where a relief centre has been set up at a sports reserve in the suburb of Wendouree and another centre open at Ararat.
Victoria Premier Jacinta Allan said spot fires had been thrown hundreds of metres ahead of the fire front and urged people to stay on top of emergency alerts.
"This is a fire situation that is continuing to evolve very quickly and there will be ongoing updates both to the broader Victorian community but particularly, too, to people in the local area as this fire continues to move," she said.
V/Line services on the Ararat Line and 11 bus routes have been suspended but no school closures are expected on Friday.
Langi Kal Kal Prison is located near the fire and its emergency response plan has been activated, Emergency Minister Jaclyn Symes said.
She said prisoners with medical conditions exacerbated by smoke had been moved and the facility's general manager would work with authorities over the health of prisoners and staff.
More than 2100 customers were left without power due to the conditions and a further 600 are still without electricity after storms last week, the state government said on Thursday evening.
Some 29 students from schools in Beaufort and 31 patients from the town's hospital have been taken to Ballarat.
Firefighters are also battling blazes in several other states as extreme heat conditions set in.
Multiple fires are burning in Tasmania, including an out-of-control blaze in the remote central highlands near Bradys Lake.
An emergency warning has been issued for the Dee community and surrounds.
Some 20 aircraft and two dozen crews have been attempting to control that fire, Tasmania Fire Service Deputy Chief Officer Matt Lowe said.
"The fire remains uncontained, and crews are dealing with tough conditions amid strong gusty winds and dry vegetation," he said.
Western Australia has total fire bans in place for multiple districts from Gin Gin south down the Darling Range to Bunbury and Bridgetown, taking in Perth and Mandurah.
Part of the Eyre Highway is closed, shutting off the western side of the Nullarbor as an out-of-control blaze near Balladonia - where a watch and act warning is in place- burns into a third week.
Emergency services have told people at the Balladonia Roadhouse to go west towards Norseman.
South Australia's Country Fire Service has declared an extreme fire risk in the Mid North, the Murraylands, Riverland and the Upper and Lower South East regions.
