About 150 fires are still burning in New South Wales (NSW) and Queensland, feeding off tinder-dry conditions.
Fifty houses were destroyed or damaged in NSW on Tuesday but no lives were lost, officials said. At one point, fires broke out in suburbs of Sydney.
On Wednesday, blazes caused fresh emergencies in Queensland.
"The conditions are of concern to us," Queensland Premier Annastacia Palaszczuk told reporters.
The threat in NSW has been downgraded from catastrophic - the highest level - but officials urged residents to remain vigilant.