Several homes were likely lost in the fires across New South Wales, though the exact number was not known as conditions were too intense for firefighters to reach the hardest-hit areas Thursday night, state Rural Fire Service spokesman Matt Sun said. There were no reports of injuries or deaths.
Smoke from the fires blocked the sun over downtown Sydney, casting an eerie, orange haze across the city.
A cool front swept through the region as darkness fell, bringing temperatures from the mid-30s to the mid-teens Celsius (mid-90s to about 60 degrees Fahrenheit). But strong winds accompanying the front sent flames racing in new directions, bringing fresh misery to the 1,400 firefighters battling the blazes.
"This is as bad as it gets," Rural Fire Service Commissioner Shane Fitzsimmons told reporters.
The extent of the damage won't be known before dawn Friday, authorities said.
Wildfires are common throughout Australia in the warmer months. In February 2009, wildfires killed 173 people and destroyed more than 2,000 homes in Victoria state.