About 170,000 hectares has been burnt out in the state's north-east and Gippsland, where blazes are joining into larger fire fronts.
Firefighters say they have been lucky overnight with no property losses.
But the Country Fire Authority's (CFA) Gary Weir says several fires have merged.
'They've been joining over time and there is a chance under the influence of the weather we're about to get they will get pushed down towards Gippsland,' he said.
'They're burning in very remote areas a lot of them.'
'It's very hard to put containment lines directly around them.'
Townships near Mansfield are under direct threat, including Kevington, Gaffney's Creek, Knockwood, A1 Mine Settlement, Cheshunt, Rose River, Tolmie and Whitfield.
King Valley winegrower Arnie Pizzini says he has been up all night backburning.
'Everyone is very, very tired. We're all working extremely hard with each other, with our CFA units and all the volunteers who are helping in these fires,' he said.
'We've actually had power go out in the area as well. So that doesn't help matters either, because a lot of people utilise power for pumps.'
09/12/2006
Brisbane (+.[____]·:·) 'Co-Leader 2 of EA Games Gang'