The following information was taken from the BOM Climate Education Website

A dry-weather peril

The nature of the Australian environment - long periods of dry, hot weather and volatile natural vegetation - makes many parts of the country particularly vulnerable to this scourge. Southeastern Australia has the reputation of being one of the three most fire-prone areas in the world, along with southern California and southern France. The Black Friday fires in 1939 in Victoria, Ash Wednesday (1983) in Victoria and South Australia, and the 1967 fires in Tasmania, have each killed in excess of 60 Australians.

They loom as dark shadows in the consciousness of residents of these states on summer days when strong northerlies, extreme heat, and low humidity follow a long dry period. Throughout the 20th Century, many other fires have claimed lives, destroyed people's homes and livelihoods, and reduced thousands of hectares of forest to charcoal and ash.

Very little of the Australian continent is free from fires - scrub-fires may sweep even the arid regions in years when good wet season rains are followed by a long dry spell. In the spring of 1974, 15 percent of the land area of Australia burned after prolific growth during the preceding wet summer dried off and ignited. More generally, fire tends to follow a seasonal cycle: the dry summer months are the danger time for southern Australia, as are the winter months over northern Australia.

Fires and El Niño

Since serious fires in Australia usually follow long dry periods, many of the worst fires in eastern Australia accompany El Niño-Southern Oscillation events. For instance, the disastrous Ash Wednesday fires in southeastern Australia followed failure of winter and spring rains during the strong El Niño event of 1982. There is also some evidence that El Niño summers have a higher incidence of extreme temperatures (over 38°C). Over southeastern Australia, weather conditions considered dangerous enough to warrant a fire weather warning, and/or fire ban, overwhelmingly occur when the Southern Oscillation Index is negative. But not all the time. Some major fires have occurred in La Niña events: the fires of January 1939 followed a rare La Niña spring drought in southeastern Australia (in a cruel twist of irony, floods at the end of February washed out many of those made homeless by the fires!). And more recently, disastrous bushfires in Victoria's Dandenong Ranges in January 1997 accompanied a weak La Niña event.