Undetectable by humans without thermal imaging equipment, the site locations were quickly passed on to firefighters who moved to black them out, CFA region 15 operations officer Wayne Rigg said.

"We had a helicopter fly the entire area of the fire with an infra-red camera to detect hot spots, which we then recorded on GPS to produce a map for the ground crews to black out the hot spots identified," he said.

"About a dozen or so were detected and the helicopter picked up ones close to the fire edge, so they were the ones we were concentrating on blacking out first."

Mr Rigg said hot spots could be found in a range of underground material, including tree root systems and logs, and heat slowly continued to build long after the flames had passed over above.

He said they had the potential to spark a new blaze if there was flammable material nearby, hence the need to quickly move to extinguish those near the edge of New Year's Eve's 31 hectare fire site.

"It can flare up again if there is material around to burn, which is why we always black out on the fire edge," Mr Rigg said.

"Something right in the middle is less of a concern but on the edge hot and windy conditions might breach the (containment) line."

Mr Rigg said CFA crews would continue to patrol the fire site as weather conditions heated up again, but was confident the hot spots identified yesterday would not spark a new blaze.

However, he urged residents to remain vigilant in reporting smoke sightings to emergency services.

"Crews will take all the steps they can but we would ask the community to remain vigilant in reporting any fires," he said.