Update Tuesday 3pm
The fire at Bannaby near Taralga stands at 67 hectares and is being controlled.
RFS Southern Tablelands operations officer Lachlan Gilchrist said crews were on the ground working as best they could, accessing the blaze via fire trails.
It's understood aircraft are also water bombing the largely inaccessible country.
The zone was also kept busy yesterday with a blaze on Burrinjuck Road, south of Yass. Mr Gilchrist said an excavator working on a rural property made contact with powerlines, starting a grassfire.
Some 22 RFS appliances and aviation tackled what he described as the fast-running outbreak. It burnt through 46ha in the first hour and stood at 47ha on Tuesday. It is under control.
Burrinjuck Road was closed for a time to allow access for crews.
Mr Gilchrist said all other firegrounds were staying within containment lines in today's benign conditions.
"We expect that to continue into Thursday, with four to five days of rain forecast after that," he said.
"We're always cautious with forecasts but what's encouraging about this is the consistency. We're expecting about five days of rain above 10mm."
Two helicopters and remote area firefighters have been deployed to a fire that broke out in the Upper Lachlan Shire on Monday afternoon.
Two outbreaks were reported at about 2.20pm on Guineacor North Road, near Wombeyan Caves and off Newfoundland Road at Bannaby.
Southern Tablelands RFS operations officer Lachlan Gilchrist said they were about 15km apart and suspected they were one and the same fire. This was unclear due to the difficulty of accessing information. They have now been merged into one on the RFS Fires Near Me website.
"They are new ignitions started from lightning strikes from a storm in the area yesterday and are in difficult to access country," he said.
The fire is burning in recently burnt out wilderness areas.
The National Parks and Wildlife Service, remote area firefighting teams and two helicopters are working on it.
"We are keeping an eye on them but there is no significant threat to property," Mr Gilchrist said.
"...They are not running fires but they're to be expected. There was a violent thunderstorm there yesterday and we expect to see more ignitions in coming weeks due to the large number of lightning strikes. The saving grace is that we have a lot of crews in the area to patrol it."
RFS ground crews have been pulled off these outbreaks due the inaccessibility, leaving it to aerial and remote firefighting teams.
Meantime, the nearby Green Wattle Creek fire, which has now been contained, received a healthy drenching of rain on Sunday night. Mr Gilchrist said there was a foot of water over the road in places.
Also on the weekend, the RFS attended outbreaks at Robbs Lane, Chatsbury and on Laggan Road. Units quickly responded and the fires were restricted to trees. They were believed to have been caused by lightning strikes.
Despite searing temperatures on the weekend, major fires in the area, including Currowan, Green Wattle Creek and Morton, did not breach containment lines.
"It was a very hot weekend but there wasn't too much wind and some parts received a good lot of rain," Mr Gilchrist said.
"While there was a lot of smoke around, the fires remain where we want them to be."