What You Need to Know About Australian Bushfire Season

We all know the basics about bushfires. We know they can easily slip out of human control, and when an evacuation notice comes through, it’s time to evacuate. But there is plenty the average Australian wouldn’t know about these extreme events.

To help keep you as informed as possible, we’ve compiled all the interesting and essential things you need to know about bushfire season in Australia.

We often think of summer as being the key bushfire season, but for a lot of Australia, this window isn’t the greatest threat. It often depends on when the region has experienced the least rain (as dry, unwatered plants and grass help fire spread faster).

The Bureau of Meteorology has produced a terrific graphic representation of when each region of Australia is most at risk of bushfires, based on their average temperatures and annual rainfall. The northern regions tend to be most at-risk during Winter and Spring, whereas southern states are on alert during Summer and Autumn.

It might seem odd, but bushfires can create a variety of extreme weather events, such as downpours, thunder, lightning, and even tornadoes.

As hot smoke rises from a bushfire, it draws in cool air from the local area, which helps cool the plume of smoke. As it rises higher, air pressure reduces, and the plume cools further. This cooling air helps the moisture inside the smoke condense, forming a cloud called a “pyrocumulus”.

If that cloud then generates enough static electricity to produce a thunderstorm, it then becomes known as a “pyrocumulonimbus”. Those clouds have been known to strike lightning on nearby areas, starting new fires away from the original site.

On extremely rare occasions, the volatile weather conditions can even create incredibly fast winds and even tornadoes. During the fires burning west of Canberra in 2003, a local captured video of a fire tornado (an event when the pyrocumulonimbus cloud forms a tornado, sucking flames into the sky).

The punchline is that bushfire weather conditions can be as threatening as the bushfires themselves, creating events that often help the fire spread further. This can make managing bushfires all that much tougher for firefighters.

The CSIRO reports that the reaction zone of a bushfire can reach temperatures around 1,600oC. To put this figure into perspective, the Engineering Toolbox states that this temperature is enough to completely melt glass, cast iron, gold, sandstone, and a variety of other common materials.

According to the Climate Council, the are four key ways that climate change is affecting Australian bushfires:

• Hotter temperatures – Naturally, as average temperatures continue to climb, the conditions are made more likely for bushfires to grow out of control.
• Drier vegetation – Regions with lower rainfall (due to climate change) tend to have greater fuel supplies for a bushfire to use.
• Longer fire seasons – Both the increased temperatures and longer dry seasons have widened the windows for bushfires to form in Australia.
• More causes – Warmer climates tend to breed more lightning storms, with strikes that can start more fires.