In the state of New South Wales, 46 fires were out of control, including six under the "Watch and Act" alert, which is issued when public safety is at risk, the state's Rural Fire Service (RFS) said.
RFS Commissioner Shane Fitzsimmons told the media that at least 683 homes have been destroyed by the fires that were spreading throughout the state and approaching large urban areas, including west Sydney, Efe news reported.
Some 2,000 firefighters were working to contain the fires that have been keeping Sydney covered in a thick layer of smoke, which has led authorities to consider suspending several sporting events planned over the weekend.
Further north, dozen of hotspots affect the neighbouring Queensland state, where temperatures are expected to reach 40 degrees Celsius. Firefighters have ordered evacuations in several locations.
The fire season in Australia varies by area and weather conditions, although the blazes are generally recorded in the austral summer (between the months of December to March).
In recent years, bushfires in Australia - a country that is this year battling a severe drought - have increased in intensity, with many experts linking it to the effects of climate change.
The worst fires in the Oceanic country in recent decades occurred in early February 2009 in the state of Victoria, leaving 173 people dead and 414 injured, as well burning an area of 4,500 sq km.
( With inputs from IANS )