A FIRE has broken containment lines in a corner of northwest NSW already ravaged by flames.
There are 84 fires burning across the state, with 14 of them uncontained.
A total fire ban is once again in place across much of NSW as a return of hot and windy conditions prompt fears existing fires could get out of control.
Containment lines were broken early this morning in a region hit earlier this week with NSW's most destructive fire in more than a decade.
The 45,000-hectare blaze in the Warrumbungle National Park, west of Coonabarabran, has so far destroyed 51 properties.
"That fire just actually broke containment lines a little while ago," RFS Deputy Commissioner Rob Rogers said of the blaze at Gowang, which has cut the Newell Highway.
"So we are already seeing conditions flare up already. So people obviously in those areas need to take extreme caution."
Temperatures are expected to soar in many of the worst-affected areas on Friday, with the mercury climbing into the 40s in Sydney.
"When you combine that down south with winds of up to 70km/h ... then pretty well most of NSW, with the exception of the very northeast and northwest, we are going to be looking at very, very tough conditions today," Mr Rogers has told the Seven Network.
"So we really need people to be ready to act their bush survival plan and don't assume someone else has reported a fire."
Prime Minister Julia Gillard visited Coonabarabran yesterday and paid tribute to the bravery and stoicism of residents.
Other notable fires are those at Deans Gap in the Shoalhaven and Yarrabin in the Cooma-Monaro area, which have been burning continuously since threatening properties last week.