Dangerous fire conditions are sweeping across several states as Australia's southeast endures a Boxing Day scorcher.
Damaging winds will fan extreme fire danger on Thursday as hot and dry weather envelops large parts of Victoria, southwest NSW and much of eastern South Australia, with authorities bracing for the worst conditions since the 2019 Black Summer.
The mercury is set to reach the high 30s to 40s for much of Victoria and inland Australia, with the central western Queensland town of Birdsville forecast for a 47C belter.
Gusts of up to 100kmh were strong enough to bring down trees and power lines, and cause minor power outages, Bureau of Meteorology senior forecaster Dean Narramore said.
A high-pressure trough which brought temperatures in the high 30s to South Australia on Christmas Day is slowly trekking across the border to Victoria.
Temperatures are forecast to be even higher on Thursday, with all but one region of Victoria to face extreme fire risk.
Total fire bans have also been declared for SA's Mid North, Riverland, Murraylands, Upper South East and Lower South East regions.
The dangerous conditions could further fuel an out-of-control bushfire in Victoria's Grampians National Park which has been burning for days, covering more than 50,000 hectares.
Victoria State Control Centre spokesman Luke Hegarty warned people in the Grampians, The Gurdies, Bullengarook and Creswick to prepare bushfire survival plans.
"If you're in those areas, please take our advice and be gone by 10am this morning ... you need to leave those areas and move to somewhere else, somewhere safe," he said.
Strong and gusty winds had the potential to spread existing burning fires towards communities that had not been under a warning, he said.
"Any fire that starts today is likely to spread quickly and be incredibly difficult for crews to control."
Residents in the Grampians towns of Bornes Hill, Moyston and Pomonal were also ordered to leave on Wednesday as the blaze raced towards them.
By 7am on Thursday, remaining residents were told to take shelter as conditions had become too dangerous to leave.
With a warm morning already setting in over the region, Northern Grampians Shire Council mayor Karen Hyslop said she was nervously waiting to see what the day would bring.
"There's 18 aircraft out there at the moment and 300 firefighters," Ms Hyslop told ABC Radio.
"So there's a lot of people out there trying to protect us and trying to make sure that these fires can be contained."
Tasmanian firefighting personnel have been sent to assist, with the first rotation to arrive in Victoria on Thursday morning.
Emergency Management Minister Jenny McAllister said the federal government had yet to receive any formal requests for assistance, but was ready for support.
"There are as many as 300 personnel who in the coming days will be rotating through Victoria, coming in from other states and territories to support their fellow Australians," she said.
Mr Narramore said the combination of strong winds, high temperatures and dry air made for dangerous fire activity.
"Any fire that does get going or already is ongoing around the Grampians will likely be uncontrollable and uncontainable, leading to dangerous and erratic fire behaviour," he said.
Power provider AusNet warned customers that cuts could be triggered to prevent bushfires from starting and outages could last longer to ensure safety.
As a cool change washes over Victoria on Thursday night, hot, dry and windy conditions will push into parts of central northeastern NSW, bringing extreme fire danger on Friday.
Cooler weather is moving through central South Australia and will hit western Victoria by Thursday afternoon.
Central Victoria, including Melbourne, will feel relief by the evening which will extend through much of northern and eastern Victoria and southern NSW overnight and into the early hours of Friday.
