Catastrophic conditions setting in for bushfire-ravaged areas

Emergency crews are bracing for a day of horrific fire conditions with dangerous winds and stifling heat forecast for southeastern Australia.

Searing temperatures up to 45C are expected in bushfire-ravaged communities in NSW and Victoria on Saturday, creating catastrophic conditions.

Emergency Management Commissioner for Victoria Andrew Crisp warned a late cool change could bring thunderstorms and lightning that may spark new blazes.

"Don't just be focused on the fires we've got at the moment. Be thinking about where there would be other fires," he told reporters in Melbourne.

There are fears current fires could merge, including a blaze in Corryong in Victoria's northeast and another in southern NSW, he said.

The worst fires are burning in Victoria's east and on the NSW south coast, where 10 people have died and hundreds of homes have been destroyed.

Victoria has declared a state of disaster with two people confirmed dead and grave fears for 28 who cannot be accounted for in East Gippsland.

The unprecedented declaration, which triggers powers introduced after the devastating 2009 Black Saturday bushfires, allows authorities to compel people to leave.

Thousands of residents and holiday-makers fled the fire zones, choking the highways as people heeded the warnings from authorities.

The military has also been supporting the fire response, with about 1200 people evacuated from the Victorian coastal town of Mallacoota by navy vessels on Friday.

Asked whether a more national response is needed to bushfires in the future, Prime Minister Scott Morrison said agencies are already working together well.

"After every fire season, these things are reviewed, but there already is very strong coordination," he told Nine's A Current Affair on Friday.

The leader said he had been working the phones to source more overseas firefighters and aircraft to help fight the blazes and that people should expect more planes will come.

"This is what we do, as things escalate," he said.

A state of emergency has been declared in NSW and evacuation orders issued for much of the state's southeast as the Rural Fire Service warns some towns cannot be defended.

"We don't want to see anybody else killed in these fires, our pure focus for tomorrow is about the preservation of life," NSW Rural Fire Service deputy commissioner Rob Rogers said.

NSW ‘prepared’ for bushfire ‘onslaught’

Premier Gladys Berejiklian has said NSW is prepared for the dangerous conditions today, as 137 bushfires burn across NSW, with around 60 of them uncontained.

"I'm pleased to say that we've never been as prepared as we are today for the onslaught we're likely to face," she told reporters on Saturday morning.

"All of the major road networks are still open, but we can't guarantee that beyond the next few hours. So, there are still windows for people to get out."

More than 3000 firefighters are on the frontline, with 31 specialist strike teams in place across NSW.

NSW Rural Fire Service Commissioner Shane Fitzsimmons said temperatures would soar past 40C in southeastern NSW before a "volatile" southerly wind sweeps through in the afternoon.

"We're going to have a long day dominated by hot temperatures, dry atmosphere and winds coming out of the ranges," he told reporters.

"It will make for a very dangerous day and it will make for volatile fire grounds."

Extreme fire danger is forecast for six fire districts in NSW's southeast and the ACT, while severe conditions are forecast for Sydney, the Hunter and the central ranges.

Five "no go" zones have been established across broad sections of the south coast, parts of the alpine region and on fire-threatened parts of Sydney's fringes.

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Authorities are urging people there to head to cities, large towns, already-burnt areas or beaches if they hadn't already left.

Temperatures are forecast to reach 45C inland and up to 44C on the coast. Sydney's outskirts could hit 46C. A gusty southerly is forecast to reach the far south coast from mid-afternoon, reaching Sydney about midnight.

Kangaroo Island blaze ‘virtually unstoppable’

The bushfire emergency on South Australia's Kangaroo Island has eased but the blaze that raged through the western half of the island remains uncontrolled.

The warning level for the fire has been reduced to a watch and act with the Country Fire Service declaring the fire still a possible risk to lives and property in the area.

There are unconfirmed reports of many homes and other buildings being destroyed as the fire burnt first through Flinders Chase National Park and then east towards the towns of Parndana and Vivonne Bay.

At the height of the emergency, locals and tourists were urged to head for the towns of Kingscote and Peneshaw which were considered safer locations.

When the blaze broke through containment lines, the CFS warned it was "virtually unstoppable".

Local MP Leon Bignell said it had been a long night for those on the island with people camped out on the Kingscote Oval and others taking shelter in a school gymnasium.

He said locals who fled the fire would be looking for information from authorities on when they might return to their properties.

"People over here are in shock, they're scared, they're frightened," he told ABC radio on Saturday.

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