Action is being taken to remove people from danger as temperatures rise in the Illawarra and Shoalhaven.

A catastrophic fire danger rating is in place for both regions, as well as the southern highlands.

A fire at Wandandian south of Nowra is contained.

But the SES is doorknocking properties telling some people to leave or be prepared to leave.

Residents and holiday makers in the coastal towns of Sussex Inlet, Cudmirrah and Berara have been put on notice.

People camping in National Parks are also being told to head to the population centres of Nowra and Ulladulla.

New South Wales Emergency Services Minister, Mike Gallagher, says the army has joined with government agencies to mobilise all available fire fighting resources.

"It is a massive concern out there and this sadly has been borne out by experience," he said.

"Not just in Queensland and Victoria over the years but in our own experience to have all of these agencies in the one place at the one time making these decisions."