Residents and visitors have gone to Bermagui beaches after being told it is too late to leave the coastal township and people were encouraged to seek shelter as the fire approached.

NSW Rural Fire Service spokesman Greg Allan the said the fire in the west of Bermagui was heading in an easterly direction with strong winds pushing it along.

It comes as a fire generated thunderstorm has formed over three fires burning between Bermagui and Narooma which the NSW Rural Fire Service warned could result in escalated fire behaviour.

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.

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

As of 10am on Tuesday this was the situation for fires burning on the South Coast:

The fires have spurred the NSW RFS to issue and 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 was 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 this 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 north westerly direction with a front from the Tasman Sea expected to push winds in a south and south easterly 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.

The Princes Highway was closed in both directions between Batemans Bay to Moruya. It was also closed further south between Cobargo and Brogo.

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

People have been asked to avoid all non-essential travel.

Check Fires Near Me, Live Traffic and the Bureau of Meteorology for information.