Authorities urged holidaymakers in New South Wales (NSW) to head to beaches to avoid fires inland of popular resort towns, where campgrounds and caravan parks are packed.
"Seeking shelter and shoring up your security closer to the beach... is a much safer option," NSW Rural Fire Service Commissioner Shane Fitzsimmons said.
Most of the blazes have been sparked by lightning, he said, warning that conditions were volatile, with fires potentially smoldering following lightning strikes from the past two or three days.
"Under the hot, dry windy conditions we're expecting today there's every chance we could see new fires start as a result of some of that activity," Fitzsimmons said.
Fire authorities gave the all-clear for the New Year's Eve fireworks display over Sydney Harbour, even after some in the community and a state Labor politician pressed for it to be called off, citing fears of fire risk and in solidarity with other towns in the region that have been forced to cancel.
"Many of us have mixed feelings about this evening, but the important thing we take out of this is that we're a resilient state," state premier Gladys Berejiklian told reporters.
"I don't want to take a second away from the deep sense of loss and tragedy many people are feeling across the state," she said. On Monday, a volunteer firefighter lost his life, the third to die since the recent spate of wildfires began.
The 28-year-old firefighter's truck was blown over by extremely strong winds. Fitzsimmons said fire crews had described the scene as "truly horrific, a fire tornado."
In neighboring Victoria, fire officials said "multiple properties" were lost on Monday as a wind change blew through the eastern part of the state, forcing evacuations of holidaymakers.
Fire columns as high as 14 kilometers (8.7 miles) were creating their own weather systems, generating lightning and strong winds, with some towering columns of smoke like tornadoes, Victoria Country Fire Authority regional controller Peter O'Keefe said.