YASS, Australia: Australian firefighters raced to control a series of blazes Thursday before a forecast spike in temperatures brings the risk of more infernos, as harrowing stories of survival emerged.

Fires have been raging across southeast Australia for nearly a week and while many have been contained, 120 are still burning and at least 17 remain out of control in the country's most populous state, New South Wales.

A cooler weather front that brought some relief on Wednesday continued in many parts Thursday. But temperatures are set to soar again to well over 40 degrees Celsius (104 Fahrenheit) on Friday, piling pressure on firefighters.

NSW Rural Fire Service commissioner Shane Fitzsimmons said crews were working flat out on containment efforts before the heat returned.

"It's about focusing on getting as much contained and consolidated as we can ahead of a return to hotter and dryer conditions dominating much of NSW over the coming days," Fitzsimmons told ABC television.

"We're looking at temperatures across much of NSW into low-to-mid 40s and extending into the high 40s on Saturday.

"The only reprieve, if you can call it that, is that we are not expecting significant wind strengths to build."

The blazes have scorched more than 350,000 hectares (865,000 acres) of land in New South Wales alone, with one fire burning just two kilometres (1.24 miles) from a former weapons range littered with unexploded bombs.

The 5,840-hectare (14,430-acre) Deans Gap fire is near the Tianjara plateau which, until the mid-1970s, was used by the Australian Army as a practice bombing range.

"If it was required they'd be looking to put in a firebreak in that area," New South Wales Rural Fire Service spokeswoman told AFP.

Were the flames to reach the plateau, south of Sydney, it could complicate firefighting efforts, with the unexploded bombs making water-drops impossible.

While more than 100 homes were razed by fires in Tasmania state last weekend, only a handful have been destroyed nationwide since, and no deaths have been reported.

In Tasmania residents of the fishing village of Dunalley, where 90 homes and businesses were destroyed, could be allowed home Friday, police said, as incredible stories of survival emerged.

"We saw tornadoes of fire just coming across towards us and the next thing we knew everything was on fire, everywhere all around us," Tim Holmes, who took refuge in the sea under a jetty with his five young grandchildren, told the ABC.

"We were all just heads, water up to our chins just trying to breathe because... the atmosphere was so incredibly toxic."

The family survived but are now homeless.

The biggest impact has been on farmers, with vast amounts of pasture, crops and animal feed lost, as well as thousands of head of stock and agricultural infrastructure such as sheds and outbuildings.

One of the worst-hit areas is Yass Shire west of Canberra where a fire has so far burnt out 16,000 hectares and killed 10,000 sheep.

As well as New South Wales, fires continue to burn in the states of Victoria, Tasmania and Queensland, with total fire bans in place for Friday.

Wildfires are a fact of life in arid Australia, where 173 people died in the 2009 Black Saturday firestorm, the nation's worst natural disaster of modern times.

Most are ignited naturally, but in Sydney's west three teenage boys were charged with deliberately lighting a fire on Tuesday, and on Wednesday a man was charged after sparks from his angle grinder caused a blaze.