Warrumbungle national park in Coonabarabran

Warrumbungle national park in Coonabarabran Photo: Jacky Ghossein

Firefighters are mopping up a bushfire in the northwest of NSW that has destroyed 53 properties but is now behind containment lines.

More than 90 firefighters remain on the ground in Bugaldie, 8km west of Coonabarabran, where rainfall is reducing fire activity.

"Crews will continue mopping up and patrolling the fire to ensure the fire remains behind containment lines," the Rural Fire Service said in a statement on Sunday.

The devastation seen at the Warrumbungle National Park. Click for more photos

Aftermath of Warrumbungle National Park

The devastation seen at the Warrumbungle National Park. Photo: Jacky Ghossein

  • The devastation seen at the Warrumbungle National Park.
  • A fire fighter assess the damage at the Warrumbungle National Park.
  • The devastation seen at the Warrumbungle National Park.
  • The devastation seen at the Warrumbungle National Park.
  • The devastation seen at the Warrumbungle National Park.
  • The devastation seen at the Warrumbungle National Park.
  • The devastation seen at the Warrumbungle National Park.
  • The devastation seen at the Warrumbungle National Park.

As well as the 53 homes, 113 outbuildings, livestock and farm machinery were also lost in the fire, which has burnt through more than through 53,000 hectares and has an 180km perimeter.

A fire believed started by lightning on Friday night is also continuing to burn behind containment lines in Ku-ring-gai National Park north of Sydney.

The RFS says walking access to the Basin, in Pittwater, is restricted and smoke can be seen as far as the central coast.

Firefighting operations have been scaled down as firefighters, helped by milder weather conditions, gain the upper hand.

More than 100 fires are still active, but the fire danger has been downgraded to low to moderate across the state.

"But we've got a great window of opportunity and at this stage certainly we're in a much better position than we were two days ago," a spokeswoman told AAP.

In Victoria, a deadly fire raging out-of control near Aberfeldy has left the state blanketed in a cloud of smoke.

Authorities say the 56,000 hectare fire, burning in Gippsland since Thursday, has generated large amounts of smoke has created a haze across most of Melbourne.

The weather bureau says most of the smoke around Victoria today would have been generated on Thursday and Friday.

Arson squad detectives are continuing to investigate whether the fire was deliberately lit.

with Benjamin Millar