The Rural Fire Service says three fires broke out near Narrabri on Monday despite some good recent rain.
RFS Deputy Incident Controller, Brett Loughlin, says the blazes started within a 30km radius of Narrabri.
He says one was in the Bobbiwa National Park, another on Pikes Lane and the third was on a private property.
Brett Loughlin says lightning was a factor in all three and significant resources were deployed.
"Some 12 fire trucks, two helicopters and a fixed-wing water-bomber were responded to one fire and thanks to co-ordinated efforts crews were able to bring that fire under control without it posing any threat to property," he said.
"However, an area of about 25 hectares was burned out."
Brett Loughlin says one of the fires started on private property, but he says aerial observations confirmed the landholder was able to extinguish it without help from emergency services.
He says landholders need to be vigilant and check their properties as quickly as possible after a storm front moves through to ensure there are no ignition points.
"We urge landholders in bushfire-prone areas to closely monitor thunderstorm activity and if they detect a fire that's started on their property to please call '000' so we can get out there and deal with that fire as quickly as possible," he said.
"The quicker we can get on these fires the greater the chance we have of keeping them small and that's obviously in everyone's best interests."
© ABC 2013
07:24 EST A severe weather warning has been issued for Sydney and parts of New South Wales, raising the prospect of damaging winds and heavy rainfall.