After large parts of NSW and Victoria were hit hard by recent bushfires, the ongoing crisis this summer has now come to Canberra's doorstep.
The blaze burning in the Orroral Valley has been described as the worst bushfire threat to the nation's capital since the devastating Canberra bushfires in 2003.
The coming days are expected to be challenging for fire crews as they work to fight the inferno, but authorities the fire won't be extinguished any time soon.
Here is what you need to know.
Where is the fire?
The fire started in the Orroral Valley, deep within the Namadgi National Park, 40 kilometres south-west of Canberra.
The fire started about 1.50pm on January 27.
The Namadgi National Park makes up almost half of the ACT, taking up most of the southern parts of the territory.
The fire started remote bushland in rugged terrain that is inaccessible to ground crews
How big is the fire?
As of 9am on Thursday, the fire has burnt more than 15,000 hectares of bushland.
At the height of the fire emergency on Tuesday afternoon, the fire was burning at a rate of 400 hectares every hour.
On Wednesday afternoon, the fire was five times the size it was 24 hours earlier.
Spot fires and embers are causing the fire to grow rapidly.
How did it start?
The fire is believed to have started from a landing light on a defence department helicopter.
The helicopter, an MRH-90 Tapan, was transporting a team of six soldiers in the national park for a reconnaissance mission to clear landing zones for emergency services to send teams in to fight bushfires.
Chief of joint operations Lieutenant General Greg Bilton said the incident was deeply regrettable.
"When the helicopter landed yesterday afternoon we believe that the landing light - which is lit on the aircraft as a safety precaution when you're flying in difficult circumstances, such as a very smoky environment - we believe that created enough heat to set the grass on fire," Lieutenant General Bilton said.
An investigation into the cause of the fire has been launched.
The helicopter caught fire within 12 seconds of it coming down to land, defence says.
ACT Emergency Services Agency commissioner Georgeina Whelan said she would not comment further on the incident, but called it an unfortunate event.
Where is at risk?
The fire is threatening the town of Tharwa, south of Canberra.
During the height of the fire emergency on Tuesday, embers were seen within a few kilometres of the town.
An evacuation order was put in place for the town.
The fire is also moving towards some of the southern suburbs of Tuggeranong, which include Banks, Conder, Gordon, Calwell and Theodore.
While there are no immediate threat to homes at this time, emergency authorities have warned for residents to remain on alert and monitor conditions closely.
Large parts of the Namadgi National Park are also at risk, including several heritage areas.
Among them is the Orroral Homestead, which was built in the 1860s and has been the centre of preservation woks by many volunteers.
There are also several communication towers on Mount Tennant, which is near the path of the fire.
What's being done to stop the fire?
Firefighters have been working to set up containment lines to protect Tharwa and suburban parts of Canberra.
Backburning operations were carried out on Wednesday afternoon during a brief respite in extreme conditions.
The backburning was undertaken to allow crews to be able to move the fire into terrain where ground crews are able to tackle it.
Waerbombing efforts are also being carried out to reach inaccessible areas of the blaze.
Fire retardant is being dropped on critical infrastructure such as Mount Tennant tower.
Why is the fire moving so quickly?
Hot conditions and strong winds are fanning the flames and allowing it to spread quickly.
At one stage, the fire was burning at a rate of 400 hectares per hour.
Temperatures this week have been above 35 degrees and are expected to be worse going forward.
The mercury is set to rise to 41 degrees on Friday and 42 on Saturday.
Meanwhile, north-westerly winds of up to 50km/h are forecast for the weekend, causing concern for fire crews.
Not helping the situation are dry conditions seen in the Namadgi National Park in recent months.
Large parts of the national park were closed for the fire season due to the dryness with officials in December saying the area was a "tinderbox".
Ongoing drought conditions have also led to large amounts of fuel to be available for the fire, allowing it to burn quickly.
How does it compare with 2003?
ACT Chief Minister Andrew Barr has called the ongoing threat the worst fire to hit Canberra since the 2003 bushfires.
Those fires killed four people and destroyed almost 500 homes.
For many long-time Canberra residents, the fires in 2020 are bringing back traumatic memories of the fire disaster seen 17-years-ago, which also started in the Namadgi National Park before impacting suburban areas to Canberra's west.
While fire authorities say the current bushfire is "unprecedented" due to erratic conditions, bushfire experts have said forecast temperatures are not expected to be as dangerous as those seen in January 2003.
Retired CSIRO bushfire expert Phil Cheney said wind speeds in 2003 averaged at 65km/h, and predicted wind patterns wouldn't push the fire directly into suburban areas.
However, he said that forecasts can change at a moment's notice.
ESA commissioner Georgeina Whelan said emergency services have learnt lessons from the 2003 fires.
What's to come?
Fire authorities have said the worst days on the firefront will be on Friday and Saturday and that residents should be prepared.
Those in affected areas have been urged to have their bushfire survival plan in place.
Residents have been asked to monitor the ESA website for updates as well as the NSW RFS Fires Near Me app.
Want to read more? Here's some more of our coverage
- Orroral Valley fire to creep closer to Canberra
- What you need to know about the bushfires in Canberra
- Why the worst conditions are yet to come
- Banks residents on edge, but not panicking yet
- ACT could enter state of emergency as bushfire threat increases
- Tharwa braces for fire as heat rises
- The treasures in the line of fire
- Far south Canberra residents warned of threat at community meeting
- Authorities issue warning over 'disaster tourists'
- Firefront threatens historic Orroral homestead
- Namadgi blaze is Canberra's worst fire threat since 2003
