Residents have been urged to evacuate as an out-of-control bushfire in Grampians National Park picks up momentum ahead of worsening conditions.

An alert was issued on Thursday for people in Mooralla and Woohlpooer in western Victoria as fire fanned out in multiple directions.

A blaze on the Victoria Range picked up activity significantly overnight Wednesday.

Its western edge was expected to impact private land at various points between Hoffmans Road and Billywing Road.

Meanwhile, CFA volunteer firefighters were backburning between the towns of Dunkel and Cavendish to create fire breaks in the southern Grampians on Thursday.

The fire threat was about 30 kilometres away, but volunteers there were taking no chances, focusing on grass on either side of the main road that has grown up to a metre high.

Firefighters on quad bikes lit the flames while behind them, fellow volunteers on the back of trucks sprayed water.

Crews across the region have stepped up for the job, aiming to get the fire breaks done by Friday before conditions heat up further at the weekend.

Alerts were issued for multiple fires across the national park.

An emergency warning to leave was issued on Wednesday for the southern Grampians.

Blazes at Victoria Range and Cavendish were not yet under control, while those in the north were being told to monitor conditions.

The largest fire on the eastern flank of the park has been burning since before Christmas, but is under control.

The moment grazier Brett Monaghan realised an out-of-control bushfire was heading towards his sheep he went in search of a truck.

He had no time to ask for help moving 450 animals from his Brimpaen property in the northern Grampians but didn’t need to.

“It was fantastic,” Monaghan told AAP.

“When I came back there were people everywhere. Word got around a truck was coming in to move them and they just turned up.”

Locals helped him ready the flock for transport before they left to defend their own homes and properties from the blaze sparked by lightning strikes.

“When it’s the dry season and dry lightning strikes, she’s very much a dangerous place,” Monaghan said of the town.

Neighbour Tylor Ross and his father were among those staying, confident they’d done everything they could to prepare.

“I reckon we should be right, it’s just the embers and the ash that we’re worried about,” Ross said.

Evacuation orders were earlier issued in parts of the northern Grampians which prompted Wartook resident Andrew Jonas to leave.

“We’re surrounded by bush that’s not very defendable and we have no experience fighting fires,” he said.

There is concern fires at either end of the park could meet, particularly when temperatures soar to 40 degrees in the week ahead.

Local towns are still reeling from fires that started in December.

Cam McDonald runs the Grampians Horse Riding Centre near Monaghan’s land and thinks he could lose up to $15,000 in cancellations if there’s a three-week shutdown.

He said while the blaze will burn around his place due to fire breaks, he’s counting the cost after losing $20,000 earlier this summer.

“We can’t evacuate. We can’t just stick 20 horses in a truck and get out, that’s not possible,” McDonald said.

If he had his time over again, the Horsham Rural City councillor would never have set up his business next to a national park.

“We used to have two pubs here, one burned down in 2014. The other one simply shut,” he said.

“We’ve seen people leaving the district. The tourism industry has been decimated, not anybody’s fault necessarily.”

A separate fire in the state’s northwest at Little Desert National Park near Dimboola is not yet controlled but many there are counting themselves lucky.

Flames came within metres of homes with much of the town under threat, with one CFA volunteer of 35 years describing it as the worst he’d ever seen.

The fire claimed one home near the town, a second home further west and an event centre.

-with AAP