The premier of New South Wales state Barry O'Farrell declared a state of emergency.
The fires have killed one man, destroyed a total of 208 homes in New South Wales state and damaged another 122 since Thursday, the Rural Fire Service said.
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Temperatures will reach around 28 Celsius (82F) at their highest.
A minute's silence will be observed at 11am on Thursday in remembrance of those who lost their lives in the Manchester Arena attack.
New research has found those who consumed two cups had a 35% reduced risk, and for those who drank five cups, the risk halved.