The fires burning from Nowra to Broulee are more than 300,000 hectares in size.

Two people have been confirmed dead at Cobargo and one person is unaccounted for west of Narooma.

The fires are moving aggressively and there are reports of multiple properties being alight.

Power and phone coverage between South Nowra to Moruya, and potentially beyond, has been lost.

Power is unlikely to be restored for at least 24 hours.

Much of the South Coast was expected to be without phone coverage or power for the next 24 hours.

A fire-generated thunderstorm has formed over the Currowan fire - burning from Batemans Bay to Nowra in the north - creating erratic winds and spreading the fires faster.

Thousands of South Coast residents and visitors have crowded evacuation centres and fled to beaches.

As residents and visitors contend with the fire danger, there are almost 18,000 properties without power.

Some towns inland of coastal areas have been hardest hit, according to NSW Rural Fire Service commissioner Shane Fitzsimmons, with reports of schools being impacted.

"We have got reports from the field that some of the most impacted areas are in the Cobargo area, Broulee, Mogo, Fisherman's Paradise," he said.

"But there is a list of areas right across those fire grounds where we are seeing fire spreading very aggressively and impacting onto communities, people's homes and other infrastructure."

As of 7pm on Tuesday there were three fires on the South Coast at emergency warning level. There were another three burning at emergency level in the Snowy Monaro and Snowy Valleys districts.

Fires between Bermagui and Narooma were burning at such ferocity that a fire-generated thunderstorm was formed. These fires headed towards Bermagui on Tuesday morning, with residents and visitors fleeing to the beach.

People in Bermagui were told they had until 2pm on Tuesday to head north.

The Clyde Mountain fire has also escalated and people in Batemans Bay, Malua Bay and Surf Beach have been warned by text message to seek shelter.

The evacuation point at the Hanging Rock Sports Club Function Centre in Batemans Bay was full on Tuesday morning after hundreds evacuated.

Tathra, Bermagui, Batemans Bay and Broulee surf life saving clubs have all been declared evacuation centres for people seeking refuge from the bushfires.

According to Surf Life Saving NSW, about 5000 people are being sheltered at Bermagui Surf Life Saving Club.

About 1500 of these people are locals. The remaining 3500 are visitors to the area and will require accommodation tonight.

Accommodation has been found for 550 of these people but 2000 people may be without accommodation.

More than 178 people in Tathra are facing the same predicament and the community is being asked to render assistance by providing blankets and accommodation where possible.

There was reports on Tuesday morning of spot fires near the Batemans Bay evacuation point.

Mr Allan said the RFS had received multiple reports that structures had been impacted near Batemans Bay.

As of 5.30pm on Tuesday this was the situation for fires burning on the South Coast:

The fires have spurred the NSW RFS to issue an alert on social media that seven dangerous fires between Batemans Bay and the Victorian border posed a "serious threat to life".

Mr Allan said the general advice for those between Batemans Bay and the Victorian border was to take shelter towards the coast if it was safe to do so.

Canberran David Shearer was at Long Beach, north of Batemans Bay, where large clouds of smoke filled the air. He said flaming debris was falling from the sky.

The RFS has warned there is a chance coastal towns such as Batemans Bay, Ulladulla and Nowra could come under an ember attack on Tuesday.

Conditions for the fires are forecast to worsen with a wind change Tuesday afternoon that could cause fire behaviour to become "erratic", Bureau of Meteorology forecaster Abrar Shabren said.

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Winds on Tuesday morning were blowing in a northwesterly direction with a front from the Tasman Sea expected to push winds in a south and southeasterly direction.

"With that change coming in, that can affect fire behaviour and the make the fire behaviour quite erratic," Mr Shabren said.

"That wind change can increase the head of the fire or the fire wall so that can be quite problematic."

Fires have forced a number of road closures. On Monday one of the last remaining routes from the South Coast to Canberra was closed with the Snowy Mountains Highway near Bega. It is closed from both directions between the Monaro Highway and the Princes Highway.

At 9pm the Princes Highway was closed in both directions at the following sections:

The Cooma Road from Braidwood to Cooma was also closed.

NSW's Transport Management Centre also warned the Princes Highway between Nowra and Batemans Bay could close at any time on Tuesday.