Officials said heavy smoke across Sydney and much of the state is still likely.
"These conditions that we are looking at are a whole new ballgame and in a league of their own," said the commissioner of rural fire services, Shane Fitzsimmons. "The predictive charts indicate that there will be a significant impact on populated areas should all these forecasts materialize."
The situation is so bad that New South Wales Premier Barry O'Farrell declared a state of emergency for the state, which includes Sydney. The declaration gives firefighters special authority as conditions worsen.
"These powers include the right to order the public to leave or to enter an area, the right to shore up or demolish a building, and of course it also prevents people from disobeying an order given under these powers," O'Farrell said Sunday.
At least one death has been reported. A 63-year-old man died of a suspected heart attack Friday while defending his home against a blaze on the New South Wales Central Coast, the Australian Broadcasting Corporation reported.
Walter Lindner collapsed while working alongside his neighbor to save his heritage-listed homestead, according to ABC.
About 1,300 firefighters, including more than 120 from the neighboring state of Victoria, were tackling the blazes Sunday evening.
Firefighting forces from the Australian Capital Territory, a self-governing body surrounded by New South Wales, were also deployed to the Blue Mountains.
Forecasters are calling for hot, dry and windy conditions over the next few days, Seven Network reported.
CNN meteorologist Tom Sater said a front may slowly bring much-needed rain to some areas beginning Tuesday, but heavy winds might complicate firefighting efforts.