A fire that started on October 17 at Belmore River about 15km east of Kempsey burnt through nearly 3000 hectares of bushland in the Hat Head National Park before being brought under control.
Police, including arson unit officers are investigating as the fire is deemed to be suspicious.
Detectives are keen to speak with the driver of a white Nissan Patrol tabletop utility, with a broken tail light, which was seen in the area about 3pm that day, police said in a statement on Tuesday.
Police are also investigating if the fire has any links to blazes that occurred on the same day at Lighthouse Road at Arakoon, Maria River Road at Crescent Head, and Crescent Head Road at Crescent Head.
Any witnesses or anyone with information on the blazes is urged to come forward.
The Rural Fire Service said on Monday night there were 62 fires burning across the state, with 24 not contained.
A bushfire in northern NSW that sparked an emergency evacuation order has been contained but crews are preparing for renewed threats as the weather heats up.
People living in Nymboida, about 30km southwest of Grafton, were warned to seek shelter as the blaze barrelled towards homes on Monday.
The fire was downgraded to a watch and act alert, after crews used the RFS large air tanker to carry out retardant drops.
The majority of the state is forecast to experience high fire danger with high temperatures predicted to soar into the 30s on Tuesday.
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. Watch out for fire weather warnings there and possible total fire bans," he said.
Grafton in the Northern Rivers region was expected to hit 40C on Wednesday.
" I don't know if we've had many 40C temperatures in NSW this side of winter. This is certainly one of the first. It will be very, very warm there," Mr Hines said.
11°C