As Australia braces for what could be the worst day of the already deadly bushfire season, there are warnings conditions may not be survivable in some parts of the country.

And as mass evacuations continue, there are also warnings it may be too late for some people to get out ahead of scorching tempatures due today.

A staggering five emergency warnings and a further six evacuation warnings are now in place as uncontrolled bushfires threaten to gain momentum and conditions are expected to worsen today.

More than 50 blazes remained out of control across Victoria overnight as it braces for temperatures forecast to reach as high as 44C.

Strong winds are also expected, which could merge out-of-control bushfires, and threaten more lives and properties.

Eleven people have been confirmed dead in the Victoria and New South Wales bush fires and 28 people remain unaccounted for in Victoria, as fears for their safety grows. Premier Daniel Andrews this week declared a State of Disaster, allowing the government to order evacuations in an area with as many as 140,000 permanent residents and tens of thousands more vacationers.

"We have grave fears for the safety and wellbeing for those 28 who cannot be located," Andrews said.

"Some of those who were part of the original 17 were located (Thursday).

"If you can leave, you must leave."

The Murray Valley Highway is closed in both directions, and weather conditions are predicted to be extreme. They will create conditions which "may not be survivable", according to the CFA.

"You are in danger and need to act immediately to survive. The safest option is to take shelter indoors immediately. It is too late to leave," a CFA spokesperson said.

Victoria's CFA reports fire activity has "increased dramatically" to the north west of Anglers Rest, and the front is continuing to move towards Omeo, Dinner Plain and Cobungra.

The fire was expected to affect the township of Omeo in the early hours of this morning.

Bruthen was one of several regions issued evacuation notices overnight. The local fire department warned it didn't have the capacity to immediately help anyone outside the town's centre.

In a Facebook post on Friday night, Bruthen Fire Brigade captain James Nicholas said CFA & DELWP appliances for fire fighting and asset protection "will now NOT be in Bruthen until approx. 6-8am Saturday".

"Multiple fires across the region have led to reassignment of assets," he wrote.

"Expect fire activity to our northern perimeter approx. 4-5am.

"Ember attack likely afterwards (at times unknown)."

The latest advice for residents is to leave for the Sale Relief Centre.

"We are physically unable with remaining assets to conduct perimeter defence of the township," the statement continued.

"That's why you should leave NOW."

According to Nicholas, all firefighting appliances and personnel will be withdrawn to the centre of Bruthen to "defend critical infrastructure and preserve life".

"This will be based on the Bruthen Hall.

"Once again leave NOW for a relief centre and get out of town.

"This is not a decision that I wanted to make, more so needed to make. I encourage you to comply … Keep safe all."

On Friday, one of the largest evacuations in Australia's history was underway before hot weather and strong winds that were forecast to worsen the devastating wildfires raging across the country.

More than 200 fires were burning, and warnings of extreme danger to come on Saturday prompted mass evacuations. Traffic was gridlocked as people fled and firefighters escorted convoys of evacuees as fires threatened to close roads. Navy ships were called in to pluck hundreds of people stranded on beaches.

But not everyone in Mallacoota benefited from the Defence Force's help. Some of the most vulnerable people there were told they could not be evacuated.

Laura Freeman, 35, has holidayed in Mallacoota for more than two decades. She was staying at a caravan park with her husband and two children, aged 1 and 3, when the approaching fire trapped them in the town.

In the ensuing, terrifying hours, Freeman and her family watched the sky turn black and red. They spent some time sheltered in their car, but smoke seeped in and forced them out. Later, stuck indoors with dozens of others, she texted her mother, believing they were not going to make it.

The conditions were hard enough to endure as an adult, but Freeman and her husband also had to deal with the stress of keeping their children safe. At the suggestion of authorities, Freeman's son's arm was marked with an emergency contact number in black marker in case they became separated.

Freeman was relieved when she heard the ADF was going to evacuate the town, but that relief was short-lived. At a community meeting on Thursday, her husband was told the family would not be able to go with the ADF, because anyone on board the ship would have to climb a rope ladder – something the young children couldn't do.

On top of that, the couple learned aerial extraction would also be unavailable because of the weather conditions.

Freeman's family ultimately got lucky, as two privately owned "luxury" boats showed up on Thursday morning to evacuate them. They're safe and well now, but if not for the generosity of those strangers, they would still be stuck in Mallacoota.

She said the biggest frustration was their lack of access to accurate information during the ordeal. The lack of power stopped people from charging their phones, and some of the information they did get access to was misleading.

"We'd rather have no information than have misleading information, and false hope," she said.

But Freeman was also struck by the incredible strength of her fellow evacuees.