Southern acting deputy regional chief Stuart Males, of the Tasmania Fire Service, will finish his six-day deployment by the end of the week.

He has been working as a fire service liaison officer at the NSW Rural Fire Service State Operations Centre at Homebush Bay.

Mr Males was one of 20 fire agency management personnel from the fire service, Parks and Wildlife and Forestry Tasmania which left for NSW late on Friday.

Another 12 specialist fire officers arrived in NSW yesterday to replace the first team. 

The largest bushfire is the State Mine fire, between Lithgow and Bilpin, which has burnt more than 42,750 hectares.

Another major fire, the Balmoral bushfire, was also being controlled but had grown to more than 15,350 hectares by late yesterday.

Mr Males said the expected weather conditions could replicate those from early last week when the fires started.

``This is how serious the prediction is,'' he said.

``Temperatures are forecast to go back up to the mid-30s in the mountains and winds will bring very dry, hot air, gusting up to 100km/h.

``There is still the chance of fires joining up.

``The nature of the Blue Mountains means that there are little independent fires burning up in the valleys, so you can't get into them and deal with them.

``They sneak around in the lower ground and will flare up, link up and become larger.

``These are campaign fires.

``We could potentially be chasing them for the next couple of months.

``We are only in October and no significant rain for NSW is forecast on the horizon.''

Mr Males has been co-ordinating resource requests from his NSW counterparts.

He said working as part of a much larger, well-resourced team was ``phenomenal''.

Mr Males said he anticipated more requests for help from Tasmania as the fires continued.