VICTORIA is about to enter its most dangerous month historically for bushfires with the deadly Gippsland blaze still a major threat, Premier Ted Baillieu has warned.
''This is a big fire and it is likely to burn for some time,'' Mr Baillieu said of the fire that has taken a life and destroyed homes in the Seaton and Glenmaggie areas.
''It has a long way to go and the agencies are very focused on the prospect that the fire will move back into the forest and into areas that are really inaccessible to firefighters.''
At least 500 fire crews working around the clock to contain the blaze are bracing for high temperatures and strong winds expected to hit Victoria on Thursday.
Country Fire Authority and Department of Sustainability and Environment workers took advantage of milder conditions on Sunday to carry out a backburn operation to help protect towns and properties from the fire, which has already burnt out about 56,000 hectares near Aberfeldy since Thursday.
The 180-hectare backburn five kilometres south of Glenmaggie and six kilometres north-west of Heyfield was spurred by expectations temperatures will return to the high 30s by Thursday.
Mr Baillieu said firefighters were doing their best to contain the fire west of the Macalister River during the moderate weather conditions.
But he said the fire could grow quickly.
''Obviously Licola remains in the line of the fire at the moment,'' he said.
''To think that in nearly 24 hours this fire went from nothing to more than 40,000 hectares is quite staggering. It has moved very quickly, burnt very hard, come out of the forest around Seaton, it has travelled in a south-easterly direction in a sausage sort of footprint, the winds changed and the sausage has started to roll to the north-east - it has got a long way to go,'' he said.
''There is a remaining concern that if the fire gets into the wilderness area it will be very much unfightable and then if the winds turn, it will turn to the south again,'' he said.
Arson squad detectives are continuing to investigate whether the fire was deliberately lit.
Extensive stock losses are expected but the ferocity of the fire means Victoria Police are yet to be able to make a full assessment.
CFA Aberfeldy-Donnellys incident controller Ben Rankin said the fire is in steep, mountainous country.
''We've done some really good containment work up on the north-western end of the fire, around the Aberfeldy area. There's a large section of the fire though that is still requiring a significant amount of work,'' he said.
Extra bulldozers and manpower has been brought in to improve control lines. ''All of the work that we are doing for the next few days is relating to Thursday.''
Mr Rankin said the change is expected to fan the fire towards north Maffra, Heyfield and Cowwarr.
''There's definitely no end in sight at this point in time.''
Bureau of Meteorology duty meteorologist Dean Sgarbossa said Thursday's soaring temperatures, followed by strong winds associated with a cold front, will significantly raise the risk of fire.