She died in hospital after being found unconscious with serious burns.
Rural fire service commissioner Shane Fitzsimmons said the most intense fires have been seen in the northeast of New South Wales, where flames have been fanned by strong winds.
He added that firefighters found a body in a burned car near Glen Innes on Saturday.
Five others who were missing have reportedly been accounted for.
More than 70 fires were burning in New South Wales on Sunday morning and, while none were at emergency level, 36 were not under control.
More than 50 fires were burning further north in Queensland on Sunday morning - and the lightning of any outdoor fires and certain activities that could cause fires have been banned in 42 local areas across the state.
Dozens of bushfires were reported across New South Wales with at least 49 of those fires reported as uncontained.
Queensland Fire and Emergency Services acting commissioner Mike Wassing said in a statement: "We're experiencing tinder box-like conditions across much of the state and all it takes is one spark to start a fire that may burn for days."
Almost 5,000 homes have been evacuated in Queensland over the last 48 hours with many residents unable to return, according to the Australian Broadcasting Corporation.
The annual Australian fire season which peaks during the Southern Hemisphere summer has started early after an unusually warm and dry winter.
Mr Fitzsimmons said little reprieve in fire conditions could be expected over the next week or throughout the summer months of December, January and February.
He continued: "The forecast for the balance of the season continues to be driven by above-normal temperatures (and) below-average rainfall to dominate over the coming months."