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

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

Residents and visitors fled to beaches and evacuation centres.

Darkness rolled through Batemans Bay about midday as the firefront approached.

The Clyde Mountain fire burned the outskirts of Batemans Bay with businesses in the industrial area lost.

Just south, homes and businesses were lost Mogo, Malua Bay, near George Bass Drive, on Tallgums Way, at Catalina, Surf Beach and other coastal suburbs south of Batemans Bay.

Broulee, Tomakin and Rosedale were also all believed to have been affected by the fire.

The fires burning from Nowra to Broulee were more than 300,000 hectares in size on Tuesday night. The extent of damage could not be confirmed on Tuesday.

Further south, the Badja Forest Road fire hit Cobargo on Tuesday morning and the township was aflame for much of Tuesday.

The town was evacuated earlier in the morning. Two people have been confirmed dead at Cobargo and one person is unaccounted for west of Narooma.

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.

Rural Fire Service spokesman Marty Webster described devastating conditions across the coast.

"Multiple fires have taken huge runs and impacted heavily on a number of communities," he said.

"We know there have been losses around Cobargo and Verona, right thorough to Batemans Bay - not everywhere in those locations, but various locations between those points.

"A lot of the damage happened ahead of the southerly front and then some different locations came under threat after the southerly. We know there has been significant impact into places like Quaama, Cobargo, Nelligen and Mogo.

"We have had reports of property loss at Belowra and along the coastal strip to the south of Batemans Bay and in the industrial area."

On Tuesday afternoon, he said conditions had eased slightly and crews were working "to save what they can".

There were 17 evacuation centres open across NSW on Tuesday.

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.