As most of the town slept, Yass was already covered by a pall of smoke from the fire to its west. That blaze, which had already burnt out 8900 hectares, breached Black Range Road and was continuing in an easterly direction putting it on a possible collision course with Yass.

While there was no certainty what direction in which the fire would continue, RFS officials said it was important to be prepare for any possibility.

"We want people to be alert in Yass but definitely not alarmed," spokesman said.

More tankers continued to arrive by the hour to help battle the blaze which continued with a 5km eastern front, but more still were needed.

While the overnight cool and lighter winds may have helped conditions, the inability to offer air support at night and problems with visibility exacerbated problems.

Wind changes meant the fire changed direction, frontage and speed several times and shortly after midnight it forked with one fork approaching Bookham.

At this stage, the danger seems to have abated and neither town is in danger of imminent fire threat.

As always, concerned residents are urged to continue to check the RFS website for updates and to stay tuned to official radio, internet and social media updates. There is NO immediate concern for evacuation and may not be at any time in the foreseeable future.