Australian Bushfire (Wildfire) History

Australian Bushfire (Wildfire) History

New South Wales, Australia’s most populous state (with 7.27 million residents), has been scorched by at least 98 wild fires over the past week. At last count on Sunday, at least 22 were still burning out of control. Some 143,000 acres (58,000 hectares) have been charred so far with the loss of 208 homes and a single fatality (as of October 20th). NSW officials say these “are the most dangerous conditions seen in the state for 40 years”.

Herein is a brief summary of Australia’s wildfire history.



A massive smoke plume rises over the Kybean Valley in New South Wales on Sunday, October 20th. Photo from Reuters.

Australia Bushfire/Wildfire History

Australia has a long history of devastating wildfires, including one of the largest known in world history: The Black Friday Bushfire which burned across Australia’s Victoria State on (or peaking on) January 13, 1939. Some 4.5-5 million acres were scorched (7,800 square miles) and 71 died. About 75% of the entire state was affected and 1,100 homes and log mills were destroyed. Ash from the fires fell in New Zealand some 2000 miles to the east. Extreme heat preceded the fire, including the hottest temperature ever measured in New South Wales--49.7°C (121.5°F) on January 10th at Menindee.

Australia’s deadliest wildfire, and arguably the nation’s worst natural disaster, was the Black Saturday Fire of February 7-March 14, 2009. A swarm of fires burned 1.1 million acres (1720 square miles) and killed 180 (or 171-175 by some sources; many victims died in their automobiles trying to outrun the flames. 3,500 structures burned across the state of Victoria. There were a variety of causes of the fires: trees falling on power lines, lightning (one fire), sparks from machinery (one fire), and arson (at least two fires). A week before the fires erupted Melbourne endured three consecutive days of temperatures between 43.4°C (110.1°F) and 45.1°C (113.2°F) and a peak temperature of 46.4°C (115.5°F) on February 7th:





A massive bushfire approaches the town of Labertouche, Victoria (about 90km/56 miles east of Melbourne) on February 7, 2009. 180 people perished in the blazes, Australia’s deadliest wildfire. Photo from Xinhua/Reuters news agency.

Below is a list of Australia’s deadliest wildfire events in descending order:



Australia’s deadliest wildfire events since 1900. Prior to 1900 there were two significant and deadly wildfire events: one on February 6, 1851 in Victoria State that killed “about 12” and another on February 1, 1898 also in Victoria and also resulting in 12 fatalities. Source: EM-DAT, The International Disaster Database, Centre for Research on the Epidemiology of Disasters (CRED). (Note that the reference to the January 1994 fire location is in French for some reason. This should read ‘New South Wales’.)

So that’s the EM-DAT list. Here is a summary of Wikipedia’s list for significant Australian wildfires:





NOTE:

1 Hectare (ha) = 2.47 acres
1 Acre = 0.405 Hectare

As one can see there is some disagreement between the EM-DAT data and the Wikipedia references.


Wildfire Seasonality

Most of Australia’s worst (at least deadliest) wildfires occur during the late summer and early fall although this does not mean that they cannot occur at anytime of the year. In fact, the occurrence of the fire season largely depends on where you are in the country. Below is a map of the typical fire season by months of occurrence across the country:



Australia’s fire seasons by month of normal occurrence. Note that the current wildfires are taking place west of Sydney and that this region’s peak fire danger is usually in the spring or summer (which is September-February in Australia). In other words, the current fire situation is not unseasonal. Map from CSIRO (Commonwealth Scientific and Industrial Research Organization)—Australia’s national science agency.

Blair Trewin of Australia’s Bureau of Meteorology sums up the seasonality factor in this way:

”The main reason for this different seasonality is that the basic condition for extreme fire weather in coastal Australia is strong, dry winds of inland origin. On the east coast, this means westerlies or north-westerlies. Strong westerlies are most likely between August and October as the subtropical high reaches its most northward location, and become increasingly rare as one moves closer to summer. (However, if you do get strong westerlies in summer, this can be a particularly dangerous situation - January 1994 was an example of this). August-October is also the driest time of the year on the east coast, which is rainshadowed in westerlies (whereas it's a relatively wet season in Victoria and southern inland New South Wales). Since the basic precondition for very high temperatures on the coast is offshore winds strong enough to limit or eliminate sea-breeze influence, it is also not unusual for east coast locations to have their hottest day of the "summer" in spring - at some particularly exposed coastal locations it has even been known to happen in August (e.g. Yamba in 2009).”

This analysis, so far as the wind patterns are concerned, is inverse to the wildfire climatology for coastal California. The urban centers of coastal California are now in the heart of what, historically, has been their deadliest time of year for wildfire events.

Ironically, today (October 20th) is the anniversary of the U.S.’s deadliest urban wildfire event (discounting the Great Chicago fire of 1871 which was of unknown origin): The Oakland wildfire on Sunday October 20, 1991 burned 3500 homes and apartment buildings and killed 25. See this video about the event. October 25th will be the anniversary of the Cedar Fire that burned from San Diego to Los Angeles in 2003 killing 15, torching 280,000 acres, and burning 2,800 buildings. It remains the largest fire in California records.

Jeff Masters will be updating the fire situation in New South Wales this coming week in one of his daily blogs.


Christopher C. Burt
Weather Historian