Quantifying the heterogeneous impacts of drought across the distribution of wildfire scale

Abstract. Wildfire research has traditionally viewed drought as a meteorological factor, but multi-hazard frameworks highlight it as a critical driver of fire characteristics. Despite this conceptual shift, existing studies have largely focused on mere association between drought and wildfire, leaving a critical gap in quantifying drought’s impact on wildfire scale. Addressing this limitation, we analyzed observational records of nearly 12,000 wildfires in South Korea from 2000 to 2024 using the Quantile Treatment Effect (QTE) approach to quantify drought impacts on burned area and wildfire duration across the distribution of wildfire scales (0.05 to 0.95 quantile range). Our analysis showed that the influence of drought increased markedly toward the upper quantiles of the distribution of wildfire scale, leading to a maximum increase in burned area of 510 ha and wildfire duration of 1.2 days. At the upper tail, the drought-induced relative increase in burned area was up to 13.7 times higher and strongly exceeded the increase in wildfire duration. To our knowledge, this is the first study to quantify the quantile-dependent impacts of drought on wildfire characteristics using observed wildfire scale data. These findings advance our understanding of drought-wildfire interactions and provide an empirical foundation for multi-hazard wildfire risk assessments.