NBIC-ACS Stage 2 Grass Fire Danger Index - baseline scenario, 20% and 10% annual exceedance probabilities

The Grass Fire Danger Index (GFDI) is a fire weather potential index that describes how current weather conditions and recent precipitation patterns could support a fire in grassy areas. GFDI calculations are based on McArthur, A.G. (1966, 1973) and dependent on air temperature, relative humidity, wind speed and grass curing. The metric was developed with the worst event considered corresponding to a value of 100. Here we provide predicted upper-bound GFDI values across the Australian landscape, defined for a set of Annual Exceedance Probabilities. We calculate GFDI based on the latest Bureau of Meteorology historical weather reanalysis BARRA-R2, reporting modelled hourly weather conditions from 1979 to current at a spatial resolution of approximately 11 kilometres. Grass curing values are derived from the 99th percentile of the values modelled from 2000 to 2019 by the Bureau of Meteorology MODIS MapVictoria grass curing dataset. More than 400,000 data points at every location are then processed using the National Bushfire Intelligence Capability (NBIC) Extreme Values Analysis to predict extreme daily maximums and their likelihood. GFDI is used in operational contexts, including land use planning and Australian standards for building in bushfire prone areas, and it is a widely recognised fire weather metric. All these characteristics result in datasets that are a significant advancement in defining extreme fire weather, surpassing previous approaches and offering a robust foundation for informed decision-making in managing and mitigating Australia’s growing bushfire risks in a changing climate.