The Emergency Services Agency updated its advice to the community on Wednesday night regarding a number of fires burning out of control in the NSW high country.

The giant Dunns Road blaze, which is burning through Kosciuszko National Park, the Adaminaby Complex fire, north of Adaminaby, and the small Atkinsons fire were being monitored closely, the agency said.

The three fires were burning at advice level on Wednesday night.

"Our Incident Management Team, helicopters and crews on the ground remain vigilant and on high alert," the agency said in a statement.

"Together, we have the ability to predict fire behaviour and map lightning strikes after they occur. This allows us to remain alert, not alarmed.

"It also enables us to inform you at the earliest stage of fire activity in Canberra and surrounding NSW that may impact the ACT.

"We are prepared to respond to each and every incident that may occur. We are also doing everything we can to support NSW Rural Fire Service with the fires burning close to the ACT border."

The agency urged Canberrans to review their bushfire survival plan.

"On the worst bushfire day, our firefighters can't protect every home. We need you to be prepared too."

Tourists are being told to stay away from the fire-ravaged Snowy Mountains region ahead of worsening bushfire conditions on Friday.

The NSW Rural Fire Service established "tourist leave zone" on Tuesday, which extends to near Tumut in the north, Berridale in the east, near Tumburumba in the west and to the town of Delegate, in southern NSW.

Temperatures in the early 30s and northwesterly winds are predicted to increase bushfire activity in the region on Friday.