An extreme fire danger warning has been issued for the Greater Hunter, Northern Slopes and North Western regions.
Hot and dry conditions with fresh northeast to northwesterly winds will cause dangerous fire weather conditions across parts of northern and central NSW on Wednesday, the Bureau of Meteorology said.
Conditions may be exacerbated by a fresh and gusty south to southwesterly change moving through during the day and thunderstorms, which are likely to develop across the region.
Total fire bans will be in place for the Far North Coast, New England, Greater Hunter, Upper Central West Plains, North Western and Northern Slopes regions.
The majority of the state is experiencing high fire danger as crews continue to battle several bushfires on the NSW mid-north coast, many of which authorities believe were deliberately lit.
The Bureau of Meteorology's Angus Hines said Wednesday was the day of most concern.
"We have a broad area of extreme fire danger for northern NSW," he said.
Grafton in the Northern Rivers region is expected to hit 40C.
On early Tuesday evening, there were 66 bush and grass fires burning across the state, though none were out of control.
A fire that started last Tuesday at Belmore River, about 15km east of Kempsey, burnt through nearly 3000ha of bushland in the Hat Head National Park before being brought under control.
Police, including arson unit officers, are investigating after the fire was deemed to be suspicious.
9°C