Wednesday posed the most threatening day to many communities as hot, dry winds fanned six major fires that are burning in the Blue Mountains and Hunter.
Rural Fire Service Commissioner Shane Fitzsimmons, who had warned earlier the day posed significant dangers, said the risk from Wednesday's weather conditions had been avoided.
He praised crews and said their risky strategies led to the success.
Firefighters back-burned the blazes for five days, Fitzsimmons said, often in unfavorable conditions.
Although fires threatened homes Wednesday, no houses or lives were lost, the Sydney Morning Herald reported.
Thousands of Australians had been told to evacuate their homes Wednesday.
"If you don't have a plan, quite simply let me give you one -- pack the car now, head down the mountain, come down and enjoy time in the metropolitan area and allow the firefighters the freedom to move through the community to protect your homes," New South Wales Police and Emergency Services Minister Michael Gallacher said as Wednesday's threat loomed.
Blue Mountains Mayor Mark Greenhill, a volunteer firefighter, told the newspaper, "Bushfires are a reality for us and there is a lot of awareness, but nothing can prepare you for something as intense as this."
The fires -- Australia's worst since February 2009 wildfires that killed 173 people and destroyed more than 2,000 homes in neighboring Victoria state -- have destroyed at least 248 homes and other structures and damaged more than 150 others since Thursday, the Rural Fire Service said.
One man suffered a heart attack trying to protect his home.
An extreme fire-danger warning was issued Wednesday by the Bureau of Meteorology for the greater Sydney region and Hunter Valley, about 75 miles north of the state capital.
All public, parochial and independent schools in the area, including child care centers and nursery schools, were ordered closed.
Helicopters water-bombed the roaring blazes after firefighters forced the merger of two voracious fires with an overnight controlled burn, officials said.
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