The Rural Fire Service is urging Hunter Valley residents to be vigilant, ahead of scorching temperatures predicted in some areas tomorrow.
Heatwave like conditions are expected to grip much of the state R-F-S crews are today trying to contain 80 fires burning around the state before the hot weather strikes.
There are fires burning near Singleton and there are other blazes in the Great Lakes and at Gloucester.
The mercury will reach up to 43 degrees in some areas in the Hunter tomorrow and RFS Inspector Ben Shepherd says residents must be prepared.
"A number of these fires are burning in quite inaccessible terrain so firefighters are doing the best they can to try and get them under control," he said.
"Look as a result of lightning some of these fires in inaccessible areas may not actually come up until we see that onset of those warmer, windy conditions."
© ABC 2013
17:35 EDT Firefighters have put out several grass fires around Sydney and warned that any bushfires that develop will be extremely difficult to control as temperatures hit the 40 degrees Celsius mark.