A similar fire had taken place about 5km further up the same road last Thursday, Mr Detheridge-Davies said.
"It's the second one within seven days. We aren't too sure if it's just the dry weather ... [they were] basically exactly the same."
Crews from Mauriceville, Eketahuna, Masterton, a tanker from Carterton and a forestry crew worked to extinguish the fire, with members of the forestry crew staying behind until about 11am to mop up hotspots.
The cause of both fires was unknown, but may have been caused by a cigarette butt or a hot exhaust igniting fuel on the side of the road, Mr Detheridge-Davies said.
"People have to be cautious with anything that goes out the window. Anything that has the potential to start a fire - people have to take some responsibility. It's a habit to just flick it out the window."
The causes of both fires are being investigated.