POLICE are urging locals to remain vigilant and report suspicious activity, with fire conditions set to worsen from Tuesday.
A very high fire danger warning is in place for Tuesday, and total fire bans are in force for the Northern Slopes - which covers the Tamworth area - as well as the North West area.
The New England - which has fires burning across the Northern Tablelands and hundreds of firefighters on the ground - also has a very high fire danger on Tuesday.
Hot, dry and windy conditions are forecast for much of the state. New England Police Inspector Roger Best said it was "diabolical" that anyone could light a fire in the current climate.
"It's diabolical out there; doing that in the current conditions is just putting lives at risk," he said.
"Last week in Ebor, there was embers spotting a kilometre in front of the main fire front, and residents were evacuating.
"It's reprehensible that people are doing this deliberately."
Anyone found guilty of intentionally lighting a fire faces a maximum penalty of up to 21 years behind bars.
"We've already lost properties, lives, livelihoods, so do not let your actions be the one that puts others at risk, because there will be consequences that will follow," Inspector Best said.
"The firefighters have been fighting fires for weeks and months, and these are the people that are putting their lives on hold, going out there to fight these massive fires, putting themselves in the way of these blazes, and at risk, to save the lives of others."
On Monday, firefighters took advantage of easier conditions, backurning and strengthening containment lines on the Ebor fire, as well as the Moonbi fire - which has burnt out almost 5900 hectares - near Tamworth.
Scorching temperatures are expected this week, and dangerous fire conditions on Tuesday and for other parts of the region during the week. The Ebor blaze has already burnt more than 11,600 hectares by late on Monday, after being downgraded from a watch-and-act alert on Sunday night.
Inspector Best said his officers, working with fire crews, had doorknocked homes across the Northern Tablelands to warn residents they should evacuate if they weren't equipped or prepared to defend their homes.
He said police had been involved in at least nine weeks of firefighting operations, across Tenterfield, Glen Innes, Tingha and Ebor.
"We have had to tell people to leave their homes, because it is probable that they will be impacted by fire," he said.
"That really has been the message throughout these communities like Tenterfield, Tingha and Ebor.
"In some places, there has been people staying, whether they're at the front or on their roofs, using their hoses to douse embers - and, in some cases, those people have saved their properties and even helped to save their town."
Emergency services said the big dry was fuelling the fires and there was no time to be complacent.
"Cigarette butts are very easily sparking grassfires that are taking off in the dry conditions," Inspector Best said.
"The embers that would perhaps naturally extinguish when they hit the ground are now sparking fires.
"We've had people using machinery like welders, and we've had fires start from welders. Anything with a spark has the potential to cause a significant fire."
Police investigations were under way into fires across the Oxley and New England policing districts that officers suspected had been deliberately lit.
"Various community members have assisted us in the investigation, and the community has come together to provide important information," Inspector Best said.
"It's vitally important any members of the community that witness suspicious activity ... report that information, whether it is the ignition points of fires, or suspicious vehicles or persons.
"That information from the community can be the vital piece of puzzle in solving the investigation."