Australians braced for a fresh wave of bushfires on Tuesday as high temperatures and strong winds were expected to worsen conditions.
Sydney and other cities were blanketed in think smoke, disrupting transportation and prompting warnings from health authorities.
More than 100 fires are burning in New South Wales and Queensland, some since November.
The fires have already killed at least four people, destroyed more than 680 homes and burnt 2.7 million hectares (6.7 million acres) this season.
To the northwest of Sydney, several fires burning for weeks have formed a "megafire" along a front of 60 kilometers (37 miles).
Temperatures were expected to soar to above 40 degrees Celsius (104 Fahrenheit) and winds strengthening under low humidity conditions, raising fears fires could spread to more populated areas.
That combination presents "a lethal condition" for bushfires, state authorities said.
While no official evacuation order was given, some residents in parts of eastern Australia fled their homes as a precaution.