The Orroral Valley fire in bushland south of Canberra has now burned 55,234 hectares of land, with a nearly 150-kilometre-long burnt perimeter.

Emergency Services Commissioner Georgeina Whelan warned Canberra faced a new threat today as storms approached from the north-west.

"Perfect storm conditions for us would be rain and no thunder and no wind in the gap of land that has not been burnt between our southern borders of the Orroral Valley fire and the Adaminaby complex fires, however, this cannot be guaranteed," Ms Whelan said.

"Our community needs to be prepared for the impact this storm may have on our southern and western suburbs. This is why we have the entirety of the ACT State Emergency Service supported by Victorian State Emergency Service, New South Wales State Emergency Service on standby to respond.

"This will enable us to keep every firefighter on the fire ground while our storm and flood responses are ready to go."

A series of five fire breaks have been created between the fire and Tharwa and the southern Canberra suburb of Gordon, and Ms Whelan said at this stage no houses were currently at risk.

The fire is slowly burning downhill to containment lines on the northern flank, with a strip of land 50 to 100 metres taken back to bare earth, where fire fighters will look to prevent the fire from encroaching any further.

READ MORE:

As of late morning Sunday fires were still more than one kilometre from Tharwa and around 6.4 kilometres from the suburb of Gordon, and authorities would continue doorknocking Tuggeranong suburbs today.

It's estimated more than 7500 homes have been doorknocked in recent days by emergency services and defence personnel.

Fire retardant has been dropped in the area in between Mount Tennant and Tharwa to create further fire breaks and to protect properties.

Just under 100 firefighters will be working on the fire or moving into the area on Sunday, along with hundreds of defence personnel. 34 vehicles were working on the fire ground overnight, and 16 aircraft remain available today, with work already under way to lay fire suppression ahead of the blaze.

Emergency services have said multiple trees in the area have been weakened by the fire, which could pose a further risk.

The warning comes after three firefighters were injured after two trees fell on their fire truck while battling the bushfire on January 29.

ACT Chief Police Officer Ray Johnson said while the vast majority of the public had been respectful of roadblocks, a small number of disaster tourists had been trying to find sneaky ways around them to take photos.

"It's breathtakingly dangerous to divert the resources of police ... my message is that it's you that you're putting in danger and others, and we'd ask you not to do it," Mr Johnson said.

She said Canberrans could expect the total fire ban, which ends at midnight, would be extended, although that decision would be made around 4pm.

The Orroral Valley fire in the ACT and the Clear Range fire in the Michelago area are expected to merge today. "It is our assessment that it's only a matter of time," Ms Whelan said.

ACT Chief Minister Andrew Barr also praised the work of authorities.

"There are still days, and possibly weeks, ahead of us. We will continue to keep the community informed and the ESA, so ably led by Commissioner Whelan, have all done an amazing job of protecting our community and we should all be very proud of their work," Mr Barr said.

The Orroral Valley fire remains at watch and act level as of 11.30am Sunday.

The Clear Range fire in NSW is burning at an advice level.