Firefighters said that by last night more than 6500 hectares of NSW had been burnt, but fires that threatened life or property appeared to be under control.

Big fires at Peats Ridge on the Central Coast and in the Bega Valley on the South Coast were still burning huge areas of bushland last night, along with eight other smaller fires around the state.

The Premier, Nathan Rees, said he was prepared to give "every assistance available" to Victoria to alleviate the "hellish conditions" engulfing the state. He said NSW firefighting resources would not be depleted by the deployment of a taskforce to Victoria.

More than 250 NSW firefighters and 50 tankers from the Rural Fire Service and the NSW Fire Brigades were sent to Victoria yesterday. Five paramedics have joined them and four are on standby.

"NSW and Victoria have a proud history of going to each other's aid in times of great need and we will provide whatever resources Victorian emergency services require as swiftly as possible," Mr Rees said.

He said his thoughts and condolences were with Victorians but warned that NSW faced its own threat.

At Peats Ridge, about 300 hectares of Brisbane Waters National Park were incinerated.

Nearby residents battled spot fires. "I was just running around stomping out little spot fires," said Logan Smith, 18, who was staying on his father's property near the fire. "It was really hot; my eyes were stinging because of the smoke."

A neighbour, Nathan Clackson, said the fire had approached his orchards before it was contained with the help of 20 fire engines. "We had the bags packed but we weren't going to bail," he said. "I put too much into this farm."

In the Bega Valley, blustery winds from Victoria fanned seven fires in and around national parkland that had burned out an area the size of 1400 football fields.

"It's out of control. It's rugged, steep terrain," a fire incident controller, Andrew Stark, said of a fire burning near Belimbla. "The fire has so much energy in it. The humidity won't have any effect until nightfall."

Three fixed-wing aircraft and a helicopter dropped water on the fire's path to slow the flames.

Another fire that has been burning for more than a week fed on dry fuel 20 kilometres west of Pambula at Jingera Rocks. Lightning strikes were believed to have sparked the fires on the South Coast.

Another big fire was burning in the upper Hunter near Singleton.

Mr Rees said more than 500 firefighters and 40 aircraft were fighting bushfires in NSW. The state had been preparing for the hot weather all week following early forecasts, he said, and resources had been put at the ready.

Mr Rees said any arsonist found responsible for bushfires in NSW would face heavy consequences. "The penalty is up to 25 years in jail and we will throw the book at you," he said.