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We know that hot, dry and windy weather increases the risk of fires starting, but here’s what we know about what actually provides the spark.

The nine categories of bushfire ignition

Fire investigators have nine categories for the ignition sources of fires:

Smoking: Smoking isn’t as common a source of bushfire ignition as we might think. There have to be some really specific conditions for a flicked cigarette to spark a fire — temperatures generally need to be above 27 degrees Celsius, and humidity below 22 per cent. And the cigarette needs to land in a loose fuel bed, and at a quite specific angle, according to Mr Woods.

Fires that start by the roadside are more likely to be ignited by burning pieces of carbon ejected from car exhausts than a cigarette butt, he said.

However, he warned that we’re currently facing weather conditions in which a cigarette could cause a fire, and we need to take every precaution we can to avoid providing a spark.

Burning off/debris: Burning off is a regular source of bushfire ignition.

Arson: The motivations for why people commit arson are varied and complex, but arson is behind a large number of bushfires both in Australia and internationally.

While figures vary, around half of all bushfires in Australia are either known to be deliberately lit or are considered suspicious, according to the Australian Institute of Criminology.

Railway cause: Railway has its own category, as trains are a surprisingly common source of bushfires. Brake failure in trains can throw out a wall of sparks, sometimes igniting dry vegetation along the side of the tracks and across significant distances.

Burning carbon embers thrown from train engine exhausts can also start bushfires.

Campfires: Embers from campfires, and campfires that aren’t properly extinguished are a bushfire hazard. Many popular campsites have moved away from open campfires, and provide fire rings to contain embers.

Equipment use: Chainsaws, angle grinders, mowers, etc. Using grinders or welding equipment outdoors is not permitted during a fire ban because of the sparks they throw.

Sparks thrown by lawn mowers is another common way of accidentally causing a fire.

Children: Children are also categorised separately, as they are often implicated in starting fires, but usually they’re considered to be out of curiosity rather than malice.

Lightning: It’s the most common ignition source in remote areas, but not all lighting is equally likely to start a fire, .

Positively charged lightning is far more likely to start a fire, positive charges only make up about 10 per cent of lightning strikes.

Miscellaneous: Power lines, firearms, blasting, glass refraction, electric fences, and more.

Electric fences and power lines are also common sources of ignition, but glass refraction — where sunlight is concentrated through a discarded glass bottle — is so rare it’s almost a myth.