The Snowy Mountains Highway is expected to be forced to close on Friday afternoon, as firefighters brace for an afternoon of erratic weather conditions.
High temperatures and windy conditions are expected to cause new ignitions in the Dunns Road and Green Valley fires, as well as risking flare-ups of existing hot spots.
The fires are also expected to join up with the East Ournie Creek blaze.
Speaking from the fire control centre at Tumut, Bradley Stewart from the Rural Fire Service said firefighters were expecting an afternoon of low humidity, high temperatures, windy conditions and an unstable atmosphere .
He warned the winds were also likely to blow down trees that were burned in fires that swept through the Batlow and Tumbarumba areas last weekend.
These falling trees could well cut the recently restored power to Batlow and Tumbarumba.
"There are multiple fire fronts," Mr Stewart said.
"There is an extreme fire danger and erratic weather conditions."
Mr Stewart advised residents of areas expected to be affected by the fires to make sure they had the latest information and warnings from he RFS.
"Leaving is the safest option," he said.
"If you do decide to stay to defend your property, you need to be aware that fire and fallen trees could impede the ability of firefighters to reach you."
Mr Stewart said only well-prepared homes should be defended, and said the RFS prioritised life, property and then the environment when it came to allocating resources in a fire.
He also praised people who were living in fire-threatened areas.
"People are listening and moving out of harm's way," Mr Stewart said.
Mr Stewart also praised the region's volunteer firefighters.
He said the NSW fire season had started much earlier than usual with fires in Tenterfield in August.
"We've been fighting fires ever since. The Riverina volunteers have well and truly stepped up.
"People are tired, but if we don't step up and do this - do the best job we can - no one else will."