Catastrophic threat level is the most severe rating.
Wildfires are common during the Australian summer. The combination of soaring temperatures and dry, windy conditions since Friday have sparked fires that burned 50,000 acres of forests and farmland across southern Tasmania.
In New South Wales, Australia's most populous state, the fires scorched 74,000 acres. All state forests and national parks were closed as a precaution and total fire bans were in place.
In Victoria state, where fires in February 2009 killed 173 people and destroyed more than 2,000 homes, officials said two people were treated for minor burns and four were treated for smoke inhalation.
Up to 20 properties in the town of Chepstowe west of Melbourne reportedly were hit by a fire, although it was too early to know the extent of the damage, a Victoria Country Fire Authority spokeswoman said.
More than 130 fires were blazing across New South Wales, though only a few dozen houses were threatened as night fell. One home was destroyed in the village of Jugiong, northwest of the capital of Canberra, fire officials said.
A fire was burning near about 30 homes near the small town of Cooma, south of Canberra. Cooma-Monaro shire Mayor Dean Lynch told Australia's Sky News some residents had evacuated to the nearby town of Nimmitabel.
Wind gusts of more than 62 mph were recorded in some parts of the state, although a cool front moving across the region late Tuesday brought some relief and raised hopes that New South Wales might avoid major damage.