The mega fire stretching more than 600,000 hectares in southern NSW and north-east Victoria could burn for "some weeks" before crews have it contained.

The Dunns Road, East Ournie Creek, Green Valley, Talmalmo, Mount Youngal, Doubtful Gap and Adaminaby Complex bushfires finally merged on Friday night, creating a burn perimetre of 760 kilometres.

The Abbeyard fire, which is more than 70,000 hectares in size, is still actively threatening towns in the North East and Alpine areas with residents told to keep up-to-date with warnings ahead of "benign" weather predicted this week.

Ovens incident controller Paul Bates said backburning could start during the cooler conditions, but warned "we are only in early January".

"There was relatively little movement with the high fire danger conditions on Friday, there wasn't a lot of spread," Mr Bates said.

"The weather over the next few days is relatively mild with a bit more moisture in the air.

"What it means for us is that we will be able to start looking at backburning, that is bringing the burn out to control lines where we can access the edge of the fire.

"That will greatly aid containment."

Mr Bates said the priority areas included the Demon Ridge area south of Bright and south west of Harrietville.

"Depending on conditions we will start those Sunday night or Monday," he said.

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"Friday was a potentially really difficult day, but I think with the fire spread we had it was a good day for us."

Mr Bates warned that although cooler conditions were on the cards, the fire season still had a long way to go.

"The message is that it is still early January and we are going to see more days like we saw on Friday," he said.

"So the community need to be prepared listen to warnings and be aware we still have several weeks of this to go."

That same message was told by Emergency Management Victoria commissioner Andrew Crisp on Sunday when confirming the death of Victorian firefighter Bill Slade near Omeo.

Mr Slade was killed by a falling tree near Omeo on Friday.

Mr Crisp said unsafe trees was a reason why emergency services were "going slower" in getting residents back into fire-affected areas in the North East.

"Even though we have fairly benign weather conditions this is yet another reminder that we have fairly active fires out there and people need to stay across conditions in their local areas," he said.

NSW RFS issued a community newsletter on Saturday night, titled Living with a campaign fire, which warned communities in the path of the fire to use the conditions to "fine tune" their bushfire survival plans.

"These fires are still not under control, and are not likely to be contained for some weeks due to their size," the statement said.

"Residents across the area will note increased smoke and flames when the back burns area lit.

"They will also likely see an increase in aircraft movements as they drop retardant to assist with strengthening the containment lines."

Community meetings were in Harrietville, Bright and Corryong on Sunday, with meetings meetings in Mount Beauty and Myrtleford on Monday.