A second day of light rain brought relief for firefighters battling bushfires that have killed 24 people across southeastern Australia, but hot, windy conditions are expected to return later in the week, officials warned on Monday.

The rain came down all along the coast, from Sydney all the way to Melbourne, with temperatures much lower in the low 20s Celsius (low 70s Fahrenheit), down from nearly 40 degrees C (104F) in some areas over the weekend.

"There is no room for complacency, especially given we have over 130 fires burning across the state still," said Gladys Berejiklian, New South Wales state Premier, on Monday morning.

Two people were missing in the state of New South Wales and fire authorities were still trying to assess damage from fires which ravaged small towns in the southeast part of the state last week, she said.

"This morning it is all about recovery, making sure people who have been displaced have somewhere safe [to go] and it is making sure we have resources to build up the presence on the ground to clean up the roads, clean up where the rubble exists," Berejiklian said.

Fire officials said that while the rain had brought relief to firefighters and communities ravaged by fires, it posed challenges for back-burning efforts to reduce fuel for future fires and bring existing fires under control.

It's reported that in Batemans Bay on the New South Wales south coast, power was expected to remain out for several more days, and in further south in Bermagui, food and fuel were running out.

Thousands of holidaymakers and locals have been stranded on beaches at the height of the summer holiday season, taking shelter from out-of-control fires.

More than a thousand people were evacuated by two naval ships on Friday from the town of Mallacoota in Victoria state.

The bushfire season started earlier than normal this year following a three-year drought that has left much of the country's bushland tinder-dry and vulnerable to fires. More than five million hectares (12 million acres) of land have been destroyed so far this season.

Prime Minister Scott Morrison stepped up efforts to tackle the national emergency on the weekend, with an unprecedented call-up of army reservists to support firefighters, in what has been seen as a slow response by the federal government.

Warning the bushfire would go on for months, Morrison was reported to create a recovery agency to help those who have lost homes and businesses in the fires.