The blaze had increased from 37,000 hectares to 64,782ha by Monday, December 18. However, the NSW Rural Fire Service has downgraded the fire status from Emergency to Watch and Act.

The fire alert was temporarily raised to Emergency overnight to alert residents to the developing bush fire situation.

The Newell Highway remains closed to traffic in both directions.

Narrabri Fire Control Centre public information officer, Kate Carter, said the blaze broke containment lines and took a "mass run" overnight.

"Extreme conditions and unexpected winds resulted in [the fire] making its own weather conditions," she said.

"It took a run to the east, and the winds have pushed it in all directions."

Ms Carter said it was all hands-on deck in the coming hours, as weather conditions were not in fire crews' favour.

With predicted north westerly winds having the potential to push out the fire and carry embers to neighbouring towns, the firefighters are working to prevent the expansion of the firey inferno.

"NSW RFS crews from across the state, NSW fire and rescue, National Parks Wildlife, Australian Wildlife, and many more are working on the blaze," Ms Carter said.

"We are concentrating on a lot of property protection on the outreaches, where there are properties.

"Also, we have a plan to ensure up some of those containment lines in case of wind shifts along the edges where we come into private properties.

"We have some ground crews going out into the grazing area to the east trying to door knock some of the places and let people know what is happening," she said.

An evacuation centre has been set up for residents at The Crossing Theatre in Narrabri.

The NSW RFS has advised residents to remain vigilant, and if they see a fire to contact triple zero immediately.