Orroral Valley fire in Namadgi National Park downgraded to watch and act

The Orroral Valley fire in the Namadgi National Park was downgraded from an emergency warning to a "watch and act" level at 11.15pm.

Residents in Tharwa, Boboyan Road, Apollo Road and Top Naas Road have been asked to remain on alert.

The fire has burnt more than 9500 hectares and is expected to grow.

Moderate conditions were seen on the firefront overnight, allowing for fire crews to strengthen containment lines.

ACT Emergency Services Agency commissioner Georgeina Whelan said the fire remains 12 kilometres from southern suburbs in Tuggeranong and the blaze is moving to the west.

"We still have the fire moving to the west away from suburban areas of Canberra, but we still do have fire activity on all four fronts," Ms Whelan told ABC radio on Wednesday morning.

"The fire continues to grow and what we want to do is take advantage and work on containment lines and allow us to stop the flow of the fire into suburban areas."

The fire continues to also move in a north-east and easterly direction towards Mount Tennent, Tharwa, Boboyan Road and Top Naas Road.

"Today is a day where we can be constructive with the fire but we're not going to be putting the fire out any time soon," Ms Whelan said.

"The community needs to be comfortable with being uncomfortable, the fire will take some time to be extinguished."

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Residents in Tharwa were told it was too late to leave on Tuesday with 15 residents from the town spending the night in an evacuation centre set up at Erindale College.

Residents in Banks, Gordon, Conder, Calwell and Theodore have been advised to continue to monitor conditions.

Fire crews will work to do as much as they can to contain the fire on Wednesday with the Bureau of Meteorology forecasting challenging fire weather for the weekend.

The conditions are driven by high temperatures and low humidity.

The fire was seen spotting overnight with the fire growing at one stage at a speed of 400 hectares every hour.

Crews were attacking the fire from both ground and air operations.

The ESA doorknocked in Banks, Gordon and Conder on Tuesday evening.

"This is not an evacuation, the ESA has not issued an evacuation warning for these suburbs," an ESA statement said.

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It comes as the likely cause of the fire was from the landing light of a military helicopter in a clearing operation.

Tharwa resident of 42 years Kevin Hogan was staying back late on Tuesday afternoon to defend his property from possible ember attack as the Orroral Valley fire approached.

He had 2500 litres of water ready and bought a pump and hoses more than a week ago to defend his home.

"Best thing I've ever done," Mr Hogan said.

"I just had a feeling it had to happen in ACT after what's been going on everywhere else.

"I couldn't understand how a fire never started in those real windy days."

Mr Hogan was confident Tharwa village would be OK despite the approaching fire.

"We've got plenty of river water and we'll keep the town water supply up."

He felt better prepared compared with the 2003 Canberra bushfires.

Smoke was billowing into the sky from behind Mt Tennent near Mr Hogan's property as a water tanker dropped retardant on the fire.

An evacuation centre has been set up at Erindale College.

Evacuation areas for those with horses and livestock have been set up at Exhibition Park.

Ms Whelan said liaison officers had been speaking with residents in affected areas on Tuesday morning and doorknocking efforts were being carried out by defence force personnel.

If residents were unable to leave, the ESA has advised residents to:

The Emergency Services in Canberra have drawn up an evacuation plan for the city's southern suburbs if the Orroral Valley fire in the Namadgi National Park spreads to threaten housing within the ACT.

Ms Whelan urged every person in Canberra - and not just those closest to the fire - to draw up a plan for what they do in the worst case scenario.

She said her colleagues in emergency services were working with people in the transport department of the ACT government to make sure that there were enough buses available to ferry people to safety.

"We aren't catastrophising," she said, "and we don't want to alarm the community but we want the community to remain alert and to think about how they can help the Emergency Services Agency to help them."

She said the authorities were putting together plans "across the scenarios and one of those scenarios is that the southern suburbs will have to be evacuated."

Earlier, Ms Whelan said several options had been developed to address the fire, taking into account the spotting, terrain, fuel load and unpredictable nature of fire activity seen during the bushfire season.

"We need the community to remain alert not alarmed," Ms Whelan said.

Ms Whelan urged people to monitor updates on the ESA website and social media channels and through local media.

"It is important that you don't rely on just one source of information," she said.

ESA held a community meeting in Tharwa on Tuesday morning and at the community centre in Uriarra at 6pm.

A total fire ban has been declared for the ACT until midnight on Friday.

The territory is set to experience extreme heatwave conditions on Thursday and Friday with the temperature forecast to reach into the 40s.

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