Firefighters and aircraft have spent the night attacking a massive, fast-moving bushfire threatening six beach communities on the New South Wales South Coast.

Key points: The fire reached the coast on Tuesday and spread quickly towards Kioloa, Pebbly Beach, Depot Beach and Durras North

The fire reached the coast on Tuesday and spread quickly towards Kioloa, Pebbly Beach, Depot Beach and Durras North Residents in those areas, as well as Termeil and Flat Rock, are urged to shelter and protect themselves — it is too late to leave

Residents in those areas, as well as Termeil and Flat Rock, are urged to shelter and protect themselves — it is too late to leave Firefighters and aircraft are working to protect homes. Several structures, including at least one home, have been destroyed

Firefighters and aircraft are working to protect homes. Several structures, including at least one home, have been destroyed The Princes Highway is closed between Burrill Lake and the Kings Highway turnoff

The out-of-control blaze, which triggered an emergency alert on Tuesday, has trapped residents and burnt out close to 50,000 hectares of bushland north of Batemans Bay.

Despite downgrading the fire's alert status to Watch and Act in the early hours of Wednesday, authorities have continued to urge people in Kioloa, Pebbly Beach, Depot Beach, Durras North, Termeil and Flat Rock to shelter and protect themselves from the heat, as it is too late to evacuate.

The bushfire covers a long stretch of the Princes Highway, forcing the road to be closed between Burrill Lake and the Kings Highway turnoff.

The NSW Rural Fire Service (RFS) is urging residents in South Durras to leave towards Batemans Bay, but only if it is safe to do so.

People forced to leave their homes have assembled overnight at the Ulladulla Civic Centre and the Mackay Park Function Centre in Batemans Bay.

Trapped residents determined to fight

Termeil resident Grant Miller said late on Tuesday he was scared but determined to save his home.

"I live in this beautiful house that I've spent the last 14 months rebuilding and I … I just don't want to lose it," Mr Miller said.

"I'm going to stay. And my two neighbours are committed as well."

At nearby Bawley Point, Liza Butler praised the volunteers who had worked for hours to protect properties in the beachside village.

"It's very windy and very smoky but I'm really confident in the amazing work that the Rural Fire Service is doing and the work that they did [Monday] night around Willinga Park, towards the highway and the back of the ANU coastal campus," she said.

"[It's] put Bawley Point in a really good position."

The blaze is burning through bushland near Bawley Point. ( NSW RFS Milton Brigade )

Shoalhaven RFS inspector Mark Williams confirmed reports that the bushfire, which began near Currowan, had destroyed some buildings, but said the extent of the damage was not yet known.

"Unfortunately, we do have reports of structural losses at several points … We'll get building impact assessment teams in there as soon as it's safe to do so to ascertain the damage throughout the fire ground itself."

Forecasts suggest fires will worsen

More than 100 fires continued to burn across the state overnight, and about half were uncontained.

Strong westerly winds worsened many of the blazes throughout Tuesday.

Emergency-level alerts were also issued for fires on the outskirts of Newcastle and Sydney, including an out-of-control bushfire north of Penrith.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 17 seconds 17 s Bushfire emergency continues in NSW Hunter.

NSW RFS commissioner Shane Fitzsimmons said the threat was likely to worsen rather than ease throughout the week.

"Unfortunately, that's just going to continue to deteriorate as we head into the tail end of this week," he said.

"We are expecting to see much more widespread very high and severe [alerts] right across parts of NSW, including the South Coast, particularly as we head into Thursday and Friday.

"Given the winds and given how dry the landscape is and how volatile the fire behaviour is, any one of these fires could change their alert level."