Some stayed and defended their properties, while others could only watch on as their homes burned to the ground as a mega fire front swept through the Southern Highlands.

Key points: More than 10 homes have been lost through the Southern Highlands region of NSW

More than 10 homes have been lost through the Southern Highlands region of NSW Vast swathes of prime farming land have been destroyed through the Kangaroo Valley

Vast swathes of prime farming land have been destroyed through the Kangaroo Valley The fire ripped through the region after ferocious winds whipped Currowan to the west on Saturday night

The Morton fire blaze tore through Wingello, Bundanoon and the Kangaroo Valley, threatening prime agricultural land and reducing more than a dozen homes to ash.

The RFS said five homes have been destroyed in Kangaroo Valley, the idyllic farming and tourism region south-west of Sydney, and it has warned that figure could yet climb.

NSW RFS Deputy Commissioner Rob Rogers confirmed 60 homes had been lost in a devastating start to 2020, but he expected that number to climb.

"We won't know the true cost of what we have lost yesterday until another couple of days," he said.

A firefighter assesses smouldering ground in Wingello. ( ABC News: Jake Lapham )

Homes were destroyed at Wingello, Bundanoon and through the Kangaroo Valley. ( ABC News: Jake Lapham )

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Some residents of the Kangaroo Valley area were forced to flee when the intensity of the fire reached homes up in the hills.

Kangaroo Valley firefighters said two forestry workers had to seek shelter in a dam when their ute caught alight and the fire front passed through dense bushland.

While conditions around the valley eased on Sunday, firefighters in the region continued to battle active fire fronts.

The fire tore through the valley when the Currowan bushfire jumped the Shoalhaven River — to become the Morton fire — late on Saturday night.

Ferocious southerly winds of up to 90 kilometres per hour propelled the blaze west from the NSW South Coast early Saturday evening, fanning flames directly into the valley's path

The speed and spread of the fire surpassed the modelling of the RFS as volatile conditions and a cool change swept through the region during the evening.

In Bundanoon, at least four homes were destroyed in the Morton fire as the fire front continued to savage the town on Sunday morning.

At least four homes have been lost at Bundanoon in the Morton fire. ( ABC News: Joanna Woodburn )

In the township of Wingello, the ruins of at least six houses as well as cars, trailers and farmland smouldered throughout Sunday as the town was left enveloped in smoke.

A photo of the heritage-listed home of Wingello resident May King ablaze precipitated an outpouring of support on social media when Ms King said it had burned to the ground along with everything in it.

Wingello resident John Harland stayed to defend his property. ( ABC News: Jake Lapham )

John Harland, a long-time resident of Wingello, said he'd never seen anything quite like the blaze.

The blaze jumped the Shoalhaven River on Saturday night. ( ABC News: Jake Lapham )

Mr Harland's home came under ember attack but he was well prepared with a generator, hoses and sprinklers.

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Once the fire had passed, he crossed the railway line to check on his neighbours' properties.

"We came under ember attack and lucky we didn't get more ember attacks … lucky I had a generator back up so I could keep the sprinklers going," he said.

"I came over to see how my neighbours were going and to see if I could put out any little spot fires."

Mr Harland said he stayed to defend his home despite concern from his family.

"Most of [the people who lost their homes] were the ones that left; a lot of the ones that stayed and defended only had their own place [to look after]," he said.

"It was difficult trying to convince my family to stay.

"They thought I had rocks in my head.

"I thought: I have put my last 35 years into this place and I wasn't going without a fight.

Scenes of devastation at Wingello in the Southern Highlands. ( ABC News: Nick McLaren )