Several out of control fires continued to burn in the southeastern state of Victoria on Tuesday despite more favourable conditions for firefighters.

With temperatures forecast to exceed 30 degrees Celsius across the state on Wednesday, Christmas Day, and 40 degrees Celsius on Thursday, Victorians have been advised to brace for catastrophic fire conditions.

Residents of communities that were evacuated over the weekend due to the threat posed by a major fire in the Grampians National Park, about 230 km west of Melbourne, were allowed to return to their homes for two hours on Tuesday morning to collect their belongings.

Authorities have said that they expected the fire, which has burnt more than 41,000 hectares of land in the national park over eight days, to continue burning for several weeks.

Victorian Emergency Management Commissioner Rick Nugent said that the forecast conditions would be very difficult.

"These conditions will make it far easier for fires to start and to spread and for existing fires to race off in the direction of the wind," he said on Tuesday.

Four interstate firefighting task forces and two emergency management teams were expected to arrive in Victoria on Thursday to aid the hundreds of local firefighters who have been working to contain the Grampians blaze.

Nugent said that the extra resources would be critical as the fire risk spikes after light rainfall on Sunday and Monday offered little relief, Xinhua news agency reported.

He said that authorities were continuing to undertake controlled back burning operations on Tuesday to reduce fuel loads in the national park and protect nearby towns.

The Country Fire Authority has advised anyone who can avoid traveling through affected areas over the Christmas period to do so.

Elsewhere in Australia, several small bush and grass fires in the state of New South Wales have continued to burn but were under control.

In South Australia, residents of the outer-southern Adelaide suburb of Onkaparinga Hills were urged to leave on Monday evening as firefighters battled an out-of-control bushfire. The emergency warning was downgraded on Monday night.

Courtesy Media Group: IANS