RFS public liaison officer Marty Webster said predicted southwesterly winds saw both the Big Jack Mountain and Border fires again raised to Watch and Act on Monday afternoon, leaving the towns of Candelo and Wolumla exposed to possible fire. Emergency services have been doorknocking the region advising residents to leave if that is their plan.

"Please follow advice from official sources. If you have any doubt about the validity of information seek clarification from authorities," Mr Webster said.

He advised residents that the raising of an alert level to Watch and Act "is a sign" for residents to enact their bushfire survival plans. He also confirmed aircraft support is now on hand as thick smoke clears inland allowing for increased visibility.

He said while southerly winds can be associated with cooler conditions, the northwesterly flanks of fires may be exposed to predicted strong southwesterly winds of up to 70kmh.

"We just really need the community to be realistic about what might happen today," he said.

He said the fire grounds had not been "tested" by winds from that direction, adding that areas of the Towamba Valley were likely to experience further fire activity on Monday afternoon.

Mr Webster said the newly ignited Chalk Hill Rd fire at Lochiel was likely started by lightning within pyrocumulus clouds formed by fires to the west. He said the fire is in "difficult terrain", and the predicted winds could push the northeastern front of the fire as far as Millingandi.

Firefighters also hold concerns for active fireground between Bermagui and Mogareeka, which will also be tested by the southwesterly winds, he said.

"We may see [fire] activity where we haven't seen it for a while," he said.

Mr Webster also did not discount the possible spread of the Postmans Trail fire north towards Mogilla and Bemboka.

"I trust the Bureau [of Meteorology]. I know it's not always perfect, but they're the ones with the big brains for crunching numbers," he said.

"Unfortunately they've often been right with really dire forecasts, so we're certainly preparing for their advice, and we encourage the community to do the same," he said.

Mr Webster said while "resources have been stretched at times" firefighters from across the state are helping across the firegrounds.

"For better or for worse we're the last pocket [of the state to face the bushfire crisis], and everyone's come to lend a hand."

Mr Webster said the weekend had been a "rough ride" for residents and firefighters after the Border Fire, Big Jack Mountain Fire and the Postmans Trail blaze were all elevated to emergency level.

He said said it was still too early to determine exact numbers or locations hit by fire given the evolving situation and lack of access for assessors.