Fire conditions are expected to ease on Wednesday but for residents the threat from the devastating fires remained present as thousands were without power and telecommunication lines remained down.

NSW RFS commissioner Shane Fitzsimmons confirmed on Wednesday morning that three people had lost their lives and there were grave concerns for another.

On Tuesday it was confirmed two people, 62-year-old Robert Salway and his son, 29-year-old Patrick Salway, died on their property at Wandella, about 10km north-west of Cobargo, overnight on Monday.

And on Wednesday, Commissioner Fitzsimmons confirmed a the death toll had risen to three on the South Coast and one person was still missing.

"We still have grave concerns for [another person]", he said. "[There is] limited access to the remote area to try to identify and confirm one way or the other the status of that person."

"We also have a very real challenge with a couple of isolated communities where we have reports of injuries and burn injuries to members of the public. We haven't been able to get access via roads or via aircraft," Commissioner Fitzsimmons said.

He said it was too early to tell the extent of the damage from the fires but indicated along with properties there had been considerable community infrastructures with reports that two or three schools have been heavily impacted by the fires.

"We aware of heavy tolls in terms of damage and destruction, particularly up in the South Nowra area, and places to the east of the fire burning in South Nowra," he said.

"But also the very significant activity on the bottom end of the Currowan fire, the Clyde Mountain fire, that burned down into Batemans Bay, a heavy toll had been occasioned as a result of that very fast moving fire front.

"And the Badja fire, further down south across the ranges, that's moved down right through places like Cobargo, where there's been heavy damage occasioned though those communities as well."

NSW RFS spokesman Greg Allan said it was too dangerous to get impact assessment teams on the ground in some of the hardest hit areas.

He said there had been reports of properties losses in areas south of Batemans Bay, Malua Bay, Mogo and Lake Conjola

NSW Police has announced a Public Information and Inquiry Centre has been opened to assist people in relation to bushfire information for the South Coast areas.

The telephone number to call is 1800 227 228.

NSW Police Deputy Commissioner Gary Worboys urged people to to use it only when they need to.

"It is an opportunity for people who have concerns about the fire and about the information that they're not sure in terms of where they should go or what they should do," he said

"This is not about people trying to shore up arrangements when there is already information out there to assist them. There will be no information shared with the public in terms of road, in terms of power, in terms of communications."

New South Wales Premier Gladys Berejiklian said restoring infrastructure, particularly telecommunications, would be a priority on Wednesday.

"We know that telecommunications is difficult at this stage, that there's been damage to towers but also the sheer congestion of people contacting people in those areas has resulted in telecommunications being very difficult. We ask people not to worry if they can't contact their loved ones or friends."

Ms Berejiklian also urged people to heed advice regarding road closures.

"Today will also be a day of being able to clean up and clear local roads where possible. A lot of the terrain where the fires struck yesterday down the South Coast were communities which were isolated, meaning there is only one road in and out, so there will be every effort made today to make some of the roads safe."

On Wednesday morning the Clyde Mountain fire had burnt more than 64,000 hectares, more than double the area burnt 24 hours earlier. The three fires burning between Nowra and Moruya covered close to 340,000 hectares.

Late on Tuesday three fires burning north of Bega formed to create one, with the Badja Forest Road fire at more than 165,000 hectares.

The fires remained at emergency level for most of the night before being downgraded to watch and act level early Wednesday morning.

A viral video posted on Twitter by Fire and Rescue NSW highlighted the intense conditions faced by crews on Monday. A crew from Station 509 Wyoming recorded footage showing their truck overrun by fire south of Nowra. The crew sheltered in their truck and Fire and Rescue NSW confirmed the firefighers were OK.

Fire conditions are expected to ease on Wednesday after a cool change, bringing gusts of up to 80km/h and dry lightning strikes, crossed NSW.

But conditions will deteriorate on the weekend and NSW premier Gladys Berejiklian warned conditions could be "at least as bad as what they were yesterday".

The fire danger for Wednesday in Illawarra/Shoalhaven and the Far South Coast is high, and very high in the Southern Ranges, where a total fire ban is in effect.

With the ease in conditions on Wednesday crews are going to be focusing on back burning operations and road clearing.

Major roads, including several parts of the Princes Highway linking South Coast communities, are likely to remain closed for some time due to hazards.

with Australian Associated Press