Australia’s most destructive fire weather conditions are on track to become more than four times more likely this century, with Tasmania and the temperate eucalyptus forests of southeast Australia carrying the greatest exposure.
That is according to a peer-reviewed study published this year in npj Natural Hazards, which used the McArthur Forest Fire Danger Index (FFDI) and an ensemble of dynamically downscaled CMIP6 climate projections to model how extreme fire weather will evolve under different levels of global warming.
Across Australia, once-in-twenty-year and once-in-fifty-year extreme fire events are projected to become 2.7 and 3.7 times more likely under 3°C of global warming. Whilst in southeast Australia’s eucalyptus forests those same benchmark events are projected to be 2.1-2.5 times more likely at the same warming level.
Tasmania faces the sharpest trajectory of any region studied.
Under 3°C of warming, 20-year return interval fire weather events are projected to become 3.2 times more likely, whilst 50-year return interval events are projected to become 4.1 times more likely. And even at 2°C of warming, Tasmania’s equivalent risk multipliers are 2.0 and 2.3, respectively.
The study, led by Ryan McGloin, warns that the Tasmanian findings warrant special attention, describing the projections as “particularly significant given Tasmania’s history of destructive bushfires and unique and vulnerable ecosystems that are potentially at risk of being replaced by more flammable vegetation when exposed to more frequent fires.”
The warning is grounded in history. The 1967 Black Tuesday fires killed 62 people and destroyed nearly 3,000 structures across southern Tasmania. Whilst in January 2013, fires razed 203 homes in the village of Dunalley alone. And unlike mainland forests, Tasmania’s vegetation mosaic — fire-sensitive rainforests, alpine shrublands and wet forests — faces a feedback loop in which more frequent fires progressively shift the landscape towards more flammable, fire-adapted vegetation.
A cycle, the authors say, has no natural brake.
The drivers differ by region. In Tasmania and southern Victoria, for example, projected increases in extreme fire weather are driven primarily by rising maximum temperatures, compounded by declining spring rainfall, which lifts the drought factor and lowers relative humidity on the continent’s worst fire days.
In the subtropical eucalyptus forests of southern Queensland and northern New South Wales, increasing humidity associated with a shift towards positive phases of the Southern Annular Mode partially moderates the temperature impact, resulting in the study’s lowest projected increases. There, 20-year and 50-year return interval events are still projected to become 1.8 and 2.0 times more likely at 3°C — figures the researchers describe as not immaterial.
Spring has emerged as the season of greatest concern. Severe fire weather days (FFDI ≥ 50) are projected to rise substantially in north-western and central Australia, while Very High fire weather days (FFDI between 24 and 50) are projected to increase in both the north and south. The pattern points to an earlier onset and overall lengthening of the fire season — with a shrinking window for hazard-reduction burns, a direct operational consequence for fire agencies.
The study — authored by Ryan McGloin, Ralph Trancoso, Jozef Syktus, Rohan Eccles, Nathan Toombs and Andrew Dowdy — is the first to apply the latest CMIP6 downscaled projections under different global warming levels to fire weather extremes specifically for southeast Australia’s eucalyptus forests.
For more information: McGloin, R., Trancoso, R., Syktus, J. et al. Substantial increases in the likelihood of extreme fire weather events for fire-prone ecosystems in Australia. npj Nat. Hazards 3, 28 (2026). https://doi.org/10.1038/s44304-026-00193-9
