The Department of Sustainability and Environment (DSE) said it could bring the most rain since bushfires broke out across the state's north and east almost two weeks ago.

A string of fires has so far burnt about 750,000ha, DSE spokesman Stuart Ord said.

Several Gippsland towns would again come under threat when the winds turned northerly tomorrow, he said.

''(But) the weather bureau are saying there's a chance the northerlies will bring some moisture from way up in Queensland ... their models are saying yep there's a very, very good chance of some rain coming in with this change,'' Mr Ord said.

"It won't put the fire out - we would need substantial rain to put this fire out - so what it will do is damp down the fire for some time.''

He said 4300 firefighters were involved today in creating new fire breaks and consolidating existing ones to protect towns try to contain the fires.

Rain over the following 48 hours would help greatly, Mr Ord said.

"It will allow us to get into the fire edge and put in good containment lines or further containment lines.''

Many of the fires have merged, claiming a broad swathe of bushland spanning the Great Dividing Range in Victoria's east and also the Alpine National Park.

Tomorrow's strong and gusting winds were expected to put towns south of the blaze - such as Heyfield and Briagolong - under threat.

Dargo remains surrounded by fire on three sides while another blaze is burning within 1km from houses in Walhalla.

"The last report is that it is about 500m away but it is backing down a hill, so it is burning reasonably slowly,'' Mr Ord said.

"There is no guarantee the fire won't get into the town tomorrow when the winds start to swirl a bit.''