Authorities have begun assessing the damage from heatwave-spurred bushfires that swept through two states a day earlier, as cooler conditions provided a temporary respite from blazes that have scarred the country's east coast for weeks.
Twenty-four people have been killed since the start of this year's wildfire season.
Light rain and cooler temperatures in the southeast of the country were a welcome change from the searing heat that has fuelled the devastating fires, but officials warned they were not enough to put out almost 200 fires still burning.
"It certainly is a welcome reprieve, it is psychological relief if nothing else," New South Wales (NSW) state Rural Fire Service Commissioner Shane Fitzsimmons said on the situation. "But unfortunately it is not putting out the fires."
Fire officials said temperatures were expected to rise again during the week and the next major flashpoint would come by Thursday, but it was too early to gauge the likely severity of the threat.
Fire crews across South Australia, Victoria, Tasmania and New South Wales on Monday will race to build containment lines around dozens of dangerous blazes.
SA will be under a total fire ban with warmer conditions predicted there on Wednesday, and expected to cross the eastern states on Thursday and Friday.
Victorian Premier Daniel Andrews urged people donate funds to charities, as warehouses and community halls became overwhelmed by physical donations.
He endorsed and then pledged $A2 million ($NZ2.08 million) to a bushfires fund set up by Bendigo Bank's charitable arm.
Australian comedian Celeste Barber's mammoth charity appeal for the NSW Rural Fire Service topped $A25 million on Sunday, little more than 48 hours since it began.
On Sunday, she announced the funds donated by more than 600,000 people would be shared with fire services in other states, the Red Cross, families of deceased and wildlife carers.
"I'm hearing you," she told her 6.5 million followers.
Police on Sunday confirmed a man died while helping a friend battling a fire at Batlow, south of Canberra. The 47-year-old is among 14 to have died in the past week. Four people remain missing in Victoria.
More than 6.75 million hectares of land - nearly seven times the size of Melbourne or the total mass of the Republic of Ireland - has been scorched nationwide since July last year.
Millions of wildlife have also died, though Zoos Victoria chief executive Jenny Gray said the full impact was "impossible to determine at this early stage".
Insurance claims are estimated at $A375 million since November, with a further $A56 million in insured property losses in September and October.
Amid intense criticism for his government's response to bushfires across six states, Prime Minister Scott Morrison established the NBRA on Sunday.
Modelled on the federal agency that responded to the North Queensland floods and led by a former federal police chief, it will coordinate disaster relief payments including those to small businesses and local councils.
It will also help mental health measures and run for at least two years.
The Government has already announced the rollout of up to 3000 defence force reservists to help handle the fallout from fires.
There will be 100 reservists heading to South Australia's Kangaroos Island on Monday to help with bushfire recovery.
"I want to stress the decisions we took yesterday and enacted yesterday were a statement all about the scale of this crisis," Mr Morrison said on Sunday.
Mr Morrison was asked for his message to the world, given the worldwide coverage and the hashtag "Australia on fire".
"Thank you very much for your support," he replied.
- Reuters and AAP
