Two Victorian bushfires remain a concern as the state faces severe fire conditions and total fire bans on Friday.
A fire ban has been declared for the entire state of Victoria with temperatures of 42C expected in some areas and north-westerly winds of up to 50km/h forecast.
There are 12 fires in Victoria, with two of concern to authorities, Fire Services Commissioner Craig Lapsley said.
Fire crews hope to have a fire at Kentbruck in the far southwest contained by 8am (AEDT) on Friday.
"That would be an ideal position based on the forecast weather conditions for tomorrow," he told reporters at the State Control Centre in Melbourne.
Mr Lapsley said significant resources would go to the Kentbruck fire, which has been going for nearly a week, to ensure it remained contained.
Crews will also keep a close eye on a fire at Goroke in the Wimmera region, which began two days ago and has caused authorities concern on Thursday.
Mr Lapsley said the fire was listed as "going" on Thursday afternoon.
Fire conditions in the Wimmera will be extreme on Friday, while conditions in the rest of the state will be severe, he said.
"That means we will see similar conditions to last Friday, elevated fire potential and if a fire does start it would take little for it to become uncontrolled in all parts of Victoria, with dry conditions and the weather," Mr Lapsley said.
He said Victoria is very dry particularly in central and western areas.
"Tomorrow with temperatures being high, the wind north-westerly and 40-50km/h means that fires will move very fast and will be out of control within a very short time of taking hold."
He urged people to be prepared and have a fire plan.
Serial firebugs strike six times
As firefighters in Victoria work around the clock protecting properties and lives from bush fires, police are hunting arsonists responsible for at least six suspicious fires in Melbourne's north-west.
Crews were called to three separate grass and rubbish fires at an industrial estate in Balfour Avenue, Sunshine North early this morning.
In the first incident, the firebugs set alight two stacks of lumber while a second fire was started at a nearby railway, destroying around two hectares of grassland along the train line.
Police also found two cars alight in nearby Knight Avenue.
Authorities believe it is the same person or group behind a blaze which threatened homes less than a kilometre away in Keilor East yesterday and fires deliberately started at Brimbank Park and Kealba.
MFB Commander Bob Undy told the ABC: "All fire authorities are amazed at the amount of people that are silly enough to light fires in these sort of conditions.
"It appears that it's the same people that lit the fires on the other side of the river in East Keilor last night and they're having another go tonight.
Police are also investigating three separate blazes believed to have been started deliberately at Wallan yesterday.
Acting Premier Peter Ryan has urged the public to dob in anyone acting suspiciously.
"So for everybody concerned, we need to make sure if you do see or hear anything that might be reflective of someone undertaking in this stupid course of conduct, contact the police as a matter of urgency," he said.
"It is simply unbelievable that we have idiots out there who are looking to pursue this style of activity.
"I mean to be lighting fires deliberately in the current environment that we as a state are facing is utterly inexcusable."