NSW Transport Minister and Member for Bega, Andrew Constance, has compared the South Coast fires to "an atomic bomb".
He told ABC Radio Sydney he has been out defending his home against blazes today.
"I've got to be honest with you, this isn't a bushfire, it's an atomic bomb," he told ABC Radio Sydney. "It's indescribable the hell it's caused and the devastation it's caused."
Earlier this evening an emergency warning was issued to Bega Valley residents.
Residents in the area of Toowoomba, Burragate and surrounds have been urged to seek shelter.
The NSW Rural Fire Service said people in those areas are at risk and that it's too late to leave.
Eerie scenes as darkness falls in afternoon
Skies in New South Wales and Victoria are turning eerie shades of orange, red and black, as fire conditions worsen in both states.
Street lights in the town of Berridale have been switched on to combat the smoke currently blanketing the sky an ominous shade of black.
In Jindabyne, pictures shared by 9 News journalist Tiffiny Genders show an orange sky – a warning of what's to come.
In Lake Eucumbene near NSW's Snowy Mountains and Adaminaby – where emergency warnings have been issued for blazes in the area – the sky has turned a disconcerting shade of red.
Two Kangaroo Island victims named
The Kangaroo Island bushfire victims have been identified as bush pilot Dick Lang and his son, Clayton.
Police found a burnt-out car near Parndana, with the body of the 78-year-old outback pilot inside.
His son Clayton, 43, was found on the highway 200 metres away.
The pair's family released a statement. "We are devastated to have lost two beloved members of our family – Dick Lang and his youngest son Clayton Lang – in such terrible circumstances," it said.
"Dick and Clayton were in the process of returning to the family property on Kangaroo Island after fighting a nearby fire for two days.
"Dick and Clayton were prominent members of the South Australian community who rose to the top in their chosen professions.
"'Desert Dick' Lang, 78, was a pioneering bush pilot and safari operator who opened up the outback to countless travellers from Australia and overseas.
"He first offered 4WD adventures in 1965, later adding aircraft trips to all corners of Australia and other countries, from Papua New Guinea to Africa.
"He loved the bush, he loved adventure and he loved Kangaroo Island.
"Clayton, 43, was one of Adelaide's leading plastic and reconstructive surgeons, specialising in hand surgery.
"He was supervisor of surgical training and clinical lead of hand surgery at The Queen Elizabeth Hospital. He also consulted privately.
"Dick was married to his beloved wife Helen for more than 55 years, having met her in 1959.
"They have four sons – Derek, Justin, Lachlan and Clayton – and seven grandchildren – Zac, Andre, Rose, Jasmine, Carlie; and Clayton's daughters with Christie, Sophia and Madeline.
"Helen and the family are heartbroken and reeling from this double tragedy and are touched by people's thoughts at this difficult time.
"We would like to extend our sincere thanks to the CFS volunteers, police and members of the Kangaroo Island community who are doing so much to help all those on the Island affected by these catastrophic fires."
'Not safe to leave'
NSW Premier Gladys Berejiklian has given an update on the fire situation in NSW, saying that for those in fire-threatened areas, it's no longer safe to leave.
"We have 12 fires at emergency level," the Premier said.
"We are now in a position where we are saying to people, it's not safe to move, it's not safe to leave these areas.
"We do have partial road closures in key roads across the state and, in relation to the projections we had this morning, unfortunately they are coming to fruition."
She said that the mid 40 temperatures, combined with the wind contiions mean the situation is exacerbated, and "we have still to hit the worst of it."
"If you are in one of the fire zones, adhere to the RFS advice," the Premier urged.
"The single source of truth is the RFS advice, please follow that advice to make sure you are in as safe a position as possible."
RFS Commissioner Shane Fitzsimmons said there are currently 148 fires burning across the state.
"It's too late to leave," the Commissioner said.
"Your option for safety is to shelter as the fire approaches."
Fitzsimmons says the southerly won't move into NSW until about 5pm, and won't hit Sydney until around midnight.
"It's going to be a very long afternoon and evening and, as that southerly approaches, it's going to be a volatile southerly with wind strengths up to 80 km/h or more.
"A long, difficult few hours, a dangerous few hours given the amount of emergency alerts out there".
Conditions continue to deteriorate in NSW and Victoria
A dozen bushfires have hit "emergency" warning level across NSW with soaring temperatures and strong winds fanning flames as much of the state remains in extreme fire danger.
NSW Rural Fire Service community safety officer Marty Webster says there is an "enormous" amount of fire in southern NSW and conditions have been worsening in line with forecasts.
"It felt this morning we may possibly get away (with it) but things are starting to unfold the way it was suggested," he told ABC.
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"Our grave concern is for people who haven't acted on our advice and are in bushland areas."
At one point on Saturday afternoon, there were 12 fires burning at an emergency warning level.
Emergency warnings are in place for fires in the Snowy Monaro and Snowy Valley regions as well as on the South Coast and at the 268,000-hectare Green Wattle Creek blaze southwest of Sydney.
A dangerous fire-generated thunderstorm has formed over the Currowan fire between Nowra and Batemans Bay which could spark new blazes.
Premier Gladys Berejiklian earlier said authorities were well prepared for the extreme bushfire conditions.
"We've never been as prepared as we are today for the onslaught we're likely to face," the Premier said.
In Victoria, the number of emergency alerts is increasing, as towns in the state's fire-ravaged east again come under direct bushfire attack.
Erratic winds are fuelling increased fire activity and people across East Gippsland, northeast Victoria and other areas are being told it is too late to leave.
"Omeo Valley is under direct attack – which is causing significant fire spread around Omeo and Ensay," the Department of Environment Land Water and Planning posted on Facebook on Saturday afternoon.
"Firefighters are actively protecting life critical infrastructure and community assets in this area."
By mid-afternoon the number of emergency alerts had risen to 14 and was expected to increase further.
Authorities say there are 21 people missing in the East Gippsland fire zone, revised down from 28 on Friday.
Two people have been confirmed dead.