By William Ton and Samantha Lock in Melbourne

Communities have been warned it’s too late to leave as winds fanned an out-of-control bushfire in Victoria’s Grampians that has spread thousands of hectares in a matter of hours.

Eight emergency warnings were in place across the national park on Thursday night after hot and dry conditions blanketed large parts of Victoria, southwest NSW and much of eastern South Australia, fuelling the worst fire conditions since 2019’s Black Summer.

The Grampians blazes have scorched more than 70,000 hectares over 10 days, with the spread growing from 55,000ha on Thursday morning despite crews working non-stop to secure containment lines.

Authorities warned about a gusty cool change that swept across the fire zone on Thursday afternoon, saying the strong winds could develop their own conditions and make fires spread unpredictably.

“Weather conditions have changed. Winds have strengthened pushing the fire across control lines,” VicEmergency said.

People were urged to leave immediately on the entire eastern wall of Grampians National Park including northern towns surrounding Pomonal to Ledcourt to areas around Moyston and Londonderry.

The park’s southern communities of Strathmore, Willaura and Glenthompson were also told to pack up and go.

Evacuation orders also extended beyond the national park to areas surrounding Maroona to Westmere, south of Ararat.

People in Mafeking, Bornes Hill, Kia Ora, Willaura North and communities surrounding Halls Gap and Bellfield were told to seek shelter because it was too late to leave.

Mobile and internet services were blacked out when fires damaged a communications tower near Bornes Hill.

People in the larger population centres of Stawell, Ararat and Streatham were on alert amid fast-changing conditions.

The mercury reached the high 30s or higher for much of Victoria and inland Australia on Thursday, while fire crews in the Grampians braced for the impact of the westerly wind change that came in two waves in the afternoon.

The change pushed flames southeast as they blew embers ahead of the main fire front, leading to spot fires, Victoria State Control Centre spokesman Luke Hegarty said.

However, the change would bring a welcome easing of conditions.

“As the wind change moves through the state we will see a reduction in temperatures, an increase in humidity and, thankfully, a reduction in the fire risk,” he told reporters.

All but one region of Victoria faced an extreme bushfire risk on Boxing Day, with fire bans also declared for numerous regions in South Australia.

Emergency Management Commissioner Rick Nugent said Victorian fires in Bullengarook, The Gurdies and Creswick also remained a concern.

The Grampians fires have caused significant damage to the environment, fencing, outbuildings and sheds, and resulted in stock losses.

There were no reports of homes destroyed but Mr Nugent told reporters he “wouldn’t be surprised at some point if we do have residential losses”.

Premier Jacinta Allan delivered a stern message about conditions on Thursday.

“Today’s a day of total fire ban across Victoria. Don’t be a dickhead. No fires to be lit,” she posted on social media.

Despite cooler conditions on Friday, Deputy Premier Ben Carroll warned dangerous fire conditions were set to push through to Saturday.

While Victoria has a cool reprieve on Thursday night, hot, dry conditions will move into central northeastern NSW, bringing extreme danger on Friday.

Total fire bans have been declared for the Hunter, Greater Sydney, North Western and Northern Slopes regions.