Largest grassland wildfire (mega-complex)

Wildfires come in several forms and can be measured in various ways. They are notoriously difficult to compare, particularly between those from different eras and those in remote regions where the accuracy of equipment and techniques vary drastically. Not only that, but the definition of different types of wildfire also varies. The most likely largest grassland fire mega-complex (i.e., an outbreak of wildfires that occur concurrently in a single region) in recorded history was the six-month summer season of 1974–75 in Australia. The mass conflagrations burned a swathe of around 117 million hectares (289.1 million acres) across several states in central Australia; 45 million hectares (111.2 million acres) were affected in the Northern Territory alone. The total area of bush burned over the season equates to about 15% of the entire continent.

One particular bushfire of note during the 1974–75 season occurred in the Barkly Tableland of northern Australia and alone covered an estimated 2.4 million hectares (6 million acres).

Some of the bushfires in the unprecedented season were ignited intentionally by pastoral farmers, however the majority were sparked by lightning.

Another notable series of bushfires in Australian history were the “Black Thursday” fires of 6 February 1851, which occurred in the state of Victoria. They are reported to have burned approximately 5 million hectares (12.4 million acres) of grassland in a single day. It resulted in the deaths of 12 people, as well as more than 1 million sheep and thousands of cattle.