[Source: AAP Image/Diego Fedele]

A cool change has given fire crews a chance to create more fire breaks and assess damage as they continue to battle a massive bushfire in a Victorian national park.

The out-of-control blaze has scorched more than 74,000 hectares of bushland, about the size of Singapore.

“That does mean there’s a lot of work for crews to do,” State Control Centre spokesman Luke Hegarty said.

“Both in terms of controlling the fire and undertaking assessment work to understand what yesterday’s fire spread has meant in terms of impacts to local communities, to local infrastructure.”

Friday’s two remaining emergency alerts have been down downgraded to Watch and Act warnings, but it is not safe to return for people who evacuated Halls Gap, Bellfield, Bellfield Settlement and Flat Rock Crossing.

Emergency relief centres have been set up at Ararat, Stawell and Hamilton.

About 600 firefighters and emergency services staff were working on the fire at any time, with reinforcements stationed at nearby Ballarat, between the fire and Melbourne.

“We’ve got the four task forces, so specialist firefighters coming in from interstate,” Mr Hegarty said.

“That’ll give the crews locally a bit of a hand, particularly with some of the work that needs to be done in the national park itself.”

Federal Emergency Management Minister Jenny McAllister noted national firefighting aircraft had been deployed and thanked interstate crews giving up their Christmas break to fight alongside Victorians.

“That’s obviously a really welcome gesture of solidarity from people in other states,” she told Sky News.

“They’ve come down to Victoria and really trying to support their fellow Australians at a pretty difficult time.”

Emergency Management Commissioner Rick Nugent said the Grampians fire was likely to burn for weeks even with hundreds of personnel on the ground fighting it.

“The conditions are such that it will be extremely difficult to put out,” he said.

More than 200 homes were still without power on Friday, according to energy distributor Powercor.

“We are working with emergency service agencies to safely gain access to the area to allow us to assess the damage and conduct repairs,” a spokesman said.

As Victorians enjoy a reprieve, the hot, dry and windy conditions are pushing into parts of central northeastern NSW, bringing extreme fire danger on Friday.

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