The battle to control a bushfire burning in the Brindabella Ranges, west of Canberra, will continue on the ground and in the air today, after the alert level was downgraded from "watch and act" to "advice".

A thunderstorm on Friday afternoon had minimal impact on the blaze, which had grown to 175 hectares by Saturday morning, with rain barely reaching the site.

Key points: A bushfire in south-west ACT is still seven kilometres away from closest suburb

A bushfire in south-west ACT is still seven kilometres away from closest suburb The blaze is 175 hectares, with no immediate threat to homes

The blaze is 175 hectares, with no immediate threat to homes A thunderstorm brought damaging winds to Canberra last night, but only 1.4 millimetres of rain reached the fire-ground

The fire started at Pierces Creek on Thursday night, moved fast towards Canberra on Friday, reaching eight kilometres away from the closest suburb of Kambah for most of the day.

By 8:00am on Saturday it was seven kilometres from the suburb.

The ACT Emergency Services Agency (ESA) said the fire was still uncontrolled, but there was no immediate danger to the community.

Incident controller Paul Flynn said 10 fire crews worked hard to backburn the blaze overnight. Mr Flynn said this work of battling the bushfire with controlled flames was responsible for much of the fire area, and the out-of-control section had to grown significantly.

He said they would continue to try to extinguish the fire, particularly on the eastern side, which faces the city of Canberra.

"We will still be trying to wrap the fire up by cutting in fire lines, especially on the eastern side as that is city side and that is where we are still concerned," he said.

"But we have been pretty successful at tidying up the western edge and the southern point of the fire."

He said five helicopters, two graders and three bulldozers will support 13 ACT Rural Fire Services fire crews today.

There was a "watch and act" alert for the erratic blaze for more than 12 hours on Friday.

The bushfire broke out about 8 kilometres from south Canberra after it was sparked from a burnt-out car. ( Supplied: Nick Ivey )

In the afternoon, firefighters started going door to door along the urban fringe from Kambah to Gordon in an "education activity" designed to remind residents what the alert levels meant and what they should be doing to prepare, including enacting whatever bushfire plans they had in place.

The ESA said staff attended 400 to 700 homes, which remained on standby, with no official evacuations ordered and no threat to property.

The fire is expected to grow as a thunderstorm brings powerful winds. ( ABC News: Tom Lowrey )

Galilee School in Kambah was evacuated in the morning, but all other ACT schools operated as normal.

More than 20 ACT fire crews were involved in the fight, along with six water-bombing aircraft.

New South Wales firefighters were also put on standby to help out but were eventually sent home late in the afternoon.

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The thunderstorm that hit the city in the evening eased the fire-ground conditions slightly.

The fire-ground received only 1.4 millimetres of rain, but the temperature dropped and humidity in the area increased.

Authorities warned the fire was heading in a south-easterly direction in steep terrain, with a thunderstorm whipping up powerful, damaging winds in the evening.

A number of trees across Canberra were knocked over and some parts of the city lost power.

There was also a haze over the city, but the ESA said that was dust from inland New South Wales, rather than smoke from the fire.

Rural properties in greatest danger

ACT Emergency Services Commissioner Dominic Lane said despite the fact suburban Canberra was not immediately under threat from the fire, rural properties could be at risk as the fire was difficult to predict.

Sorry, this video has expired Strong winds threaten to speed up an already erratic fire. (Photo: Tom Lowrey)

"The principle threat at this point in time is to the rural area around Pierces Creek and Tidbinbilla — that's why we have firefighting resources there to protect those homes and the surrounding outbuildings on those farms," he said.

"But in Canberra, because of the nature of our city and the closeness of the bush to many parts of Canberra, homes in the bushfire-prone area will come under threat if the fire gets closer.

Map Bushfire threatening Canberra's south-west

Burnt-out car sparks blaze

The Canberra Deep Space Communication Complex at Paddys River says normal contact with spacecraft is continuing. ( Twitter: CanberraDSN )

Firefighters said the blaze started from a burnt-out car and took hold in the neighbouring pine forest.

About 150 Year 3 and 4 students from Miles Franklin Primary School, who had been at the Birrigai Outdoor School at Tidbinbilla, were evacuated safely on Friday morning.

The bushfire could be seen on the hills behind Canberra on Thursday night. ( Twitter: AJ Johnston )

Student Kaleb Swan said the group struggled with smoke as they left the area.

"We had to leave early, miss one activity, so we could get away from the bushfires because the wind was heading towards Birrigai, same as the bushfire," he said.

"And we were also choking a bit on the smoke and we wanted to go home."

Bringing back memories of 2003

Kambah residents overlook the dark sky as winds pick up in the early afternoon. ( ABC News: Greg Nelson )

Anything approaching a fire emergency in Canberra inevitably triggers memories of the 2003 bushfires that killed four people and destroyed nearly 500 homes.

Laurence Buchanan lost his Duffy home 15 years ago and said there was no warning at the time, nor had he received much warning about the latest bushfire.

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"It brings back a lot of memories of 2003," he said.

"When you lose everything, just the threat of anything like this puts goose bumps up you.

"I'm expecting people to be here warning us and there's no warning."

Local horse handlers Lucy and Isabelle evacuated their animals as an early precaution.

"We were kids when the bad fires happened so we really know the consequences," Lucy said.

"We always have a bushfire season plan and ours is early evacuation.

"It's better to be safe than sorry."

Exhibition Park in the northern suburbs offered free stabling for those who needed it.