Fire crews are concerned a wind change, lightning strikes and thunderstorms will add further challenges after a devastating day of blazes.
At least a dozen are still burning out of control in NSW after a bushfire destroyed 12 homes in Koolewong, not far from built-up areas on the Central Coast.
Authorities have warned of an approaching storm is expected to bring strong winds and lightning strikes on Sunday morning, creating unfavourable conditions.
Koolewong will remain a priority for fire crews despite warnings being downgraded to watch and act, although the fire has moved towards the Woy Woy Bay area.
Residents were urged to remain on high alert when the wind change hits the region, although conditions should ease by 5am.
"We're seeing a band of lightning come across the state, that lightning is looking to head towards the Central Coast and we're concerned about the wind change that's expected to come through overnight," NSW Rural Fire Service Commissioner Trent Curtin said on Saturday afternoon.
Temperatures are expected to ease from Sunday for most of NSW and southern Australia, though the heat will build across northern Australia and WA and returning to much of the country early in the week.
Mr Curtin hoped the cooler weather would create an "excellent opportunity" for firefighters to get on top of the fires.
Prime Minister Anthony Albanese thanked emergency services for their efforts on the ground and in the air, adding that his thoughts were with residents affected by the fires.
Elsewhere, more than a dozen homes and shacks, outbuildings and cars were damaged and two firefighters were injured fighting an out-of-control fire at Dolphin Sands on Tasmania's east coast on Friday.
The fire has since been contained, although it's not safe for residents to return as access to the area remains dangerous.
Victorians will face milder temperatures on Sunday after a cold front and thunderstorms followed hot, dry and windy weather on Friday.
