Bushfires and heatwaves cause significant losses to the economy, agricultural productivity and disastrous effects on human health in Australia. The estimated annual cost of bushfires in Australia is about $300-400 million (Ashe et al. 2009). However, certain singular events can exact a much higher value into the billions. The 2009 Black Saturday bushfires were associated with an antecedent heatwave and resulted in an economic loss of ~ $4.4 Billion. Previous studies of these events have typically examined weather using the McArthur Forest Fire Danger Index (FFDI) (Engel et al. 2013) or focused on the synoptic features associated with bushfires over southeastern Australia (Engel et al. 2013, Hasson et al. 2009). Sullivan and Mathews 2013 studied the response of modelled fuel moisture content of fine fuels to heatwave conditions in the week prior to the Black Saturday bushfires. The relationship of bushfires with other extreme weather and climate events, such as heatwaves and drought, is a critical aspect of understanding bushfires but remains understudied. It suggested that heatwaves are a critical factor in the development of extreme bushfires, which account for the majority of bushfire impacts on society and the environment.

The present study focuses on the relationship between heatwaves and bushfire fuels by examining fuel moisture content, a crucial component of bushfire fuels that controls the rate of spread and intensity of fires. Fuels are classified based on their environmental response time, such as 10 and 100 hr fuels. We investigate the response of different fuel classes to heatwaves using the Excess Heat Factor (EHF) (Nairn and Fawcett 2013) index, focusing on Canberra as a specific case study area. We investigate how intense and prolonged heatwaves affect the moisture content of fuels both spatially and temporally, and present an approach that can be applied to regions elsewhere in Australia.