Weather conditions have eased since strong winds and temperatures topping 40C fed dozens of wildfires in southeastern Australia's Victoria, which declared a state of disaster on Saturday.

But officials said 12 major fires were still burning across the state.

Country Fire Authority chief officer Jason Heffernan said another "heating event" was expected towards the end of January, though its intensity was uncertain.

"We are early in the high-risk weather season," Heffernan told a news conference.

"There's been a lot of fire in the landscape. Much work will be done between now and then to contain these fires," he said.

"Whilst we join with community in the rebuilding and the relief and recovery of the fires that have been, we need to turn our minds to the fires that could be as the season continues."

More than 350 structures -- including over 65 homes -- have been lost so far in the state, officials said, with the number likely to rise as fire damage is assessed.

One person died in a fire near the town of Longwood, about two hours' drive north of state capital Melbourne, police say.

Emergency Management Commissioner Tim Wiebusch said weather conditions had become more favourable for firefighters.

"But that doesn't mean that the risk is over," he said.

"Whilst the conditions are easing in some parts of the state, even the slightest of winds are still causing those fires to move around."

High temperatures and dry winds combined last week to form some of the most dangerous bushfire conditions since the "Black Summer" blazes.

The Black Summer bushfires raged across Australia's eastern seaboard from late 2019 to early 2020, razing millions of hectares, destroying thousands of homes and blanketing cities in noxious smoke.

Australia's climate has warmed by an average of 1.51C since 1910, researchers have found, fuelling increasingly frequent extreme weather patterns over both land and sea.