Abstract

Wildfire variability in Southeastern Australia (SEA) has intensified in recent decades, posing increasing risks to ecosystems and agriculture under a changing climate. However, the mechanisms driving the recent amplification of extreme fire weather remain unclear. Using austral-summer data from 1981–2022, we quantify interannual links between the Forest Fire Danger Index (FFDI) and land–atmosphere variables. Fire Weather Days (FWD) are defined as days exceeding an extreme FFDI threshold each fire season and are validated against satellite-based burned area and fire intensity across SEA. We show that recent fire risk in SEA is characterized not by a gradual increase but by a regime shift in extreme fire weather conditions. An early-2000s transition is marked by enhanced interannual variability and an approximately fivefold increase in FWD, linked to increased positive skewness in daily FFDI. Among FFDI components, the drought factor (DF), representing hydrological stress, exhibits the largest increase in extreme occurrences, especially when co-occurring with high temperature (T) and low relative humidity (RH). The contribution of compound DF & RH & T events to total FWD more than doubles between 1981–2001 (P1) and 2002–2022 (P2). Segmented regression further reveals strengthened interannual FWD sensitivity to DF in P2. In P1, variability reflected atmospheric warming and drying, whereas P2 is characterized by intensified land–atmosphere coupling that amplifies hydrological stress and compound extremes. This transition coincides with changes in large-scale circulation, with the Southern Annular Mode (SAM) emerging as the dominant driver of FWD variability in the recent period, while ENSO exerted a stronger influence earlier. Increased FWD variability is also closely linked to interannual maize yield fluctuations across SEA. These findings highlight a hydrologically-driven regime shift in extreme fire weather and underscore the need for integrated climate-fire-agriculture risk assessment. 

An international team of researchers, affiliated with UNIST, has identified a dramatic transformation in wildfire patterns across Southeastern Australia (SEA). Analyzing data from 1981 to 2022, the research shows that since the early 2000s, the region has experienced a fivefold increase in extreme fire weather days, driven increasingly by the Southern Annular Mode (SAM) rather than the traditionally dominant El Niño–Southern Oscillation (ENSO). This shift highlights new challenges in predicting and managing wildfires under a changing climate.

Led by Professor Myong-In Lee from the Department of Civil, Urban, Earth and Environmental Engineering at UNIST, this study was conducted in collaboration with experts from the University of Hawaii and POSTECH. 

In this study, the team identified a regime shift beginning in the early 2000s, characterized by emphasized interannual variability and a sharp rise in extreme fire weather days. Over the past two decades, wildfire risk volatility has more than doubled. This change is primarily attributed to the strengthening of land-atmosphere coupling, where drought conditions intensify surface heating, creating a feedback loop that fuels more frequent and severe wildfires. 

beginning in the early 2000s, marked by heightened interannual variability and a sharp rise in extreme fire weather days. Over the past two decades, wildfire risk volatility has more than doubled. This change is primarily driven by strengthened land–atmosphere coupling: drought conditions dry out surface soils, creating a feedback loop that amplifies surface heating and fosters more frequent and severe wildfires.

While ENSO has traditionally been the main climate driver influencing Australian wildfires, recent evidence indicates that the SAM’s influence has grown, now serving as the dominant factor regulating wildfire variability.

Kiwook Kim, the main author of the study, comments, “Our findings emphasize the need for enhanced monitoring of atmospheric circulation patterns and soil moisture levels. This knowledge is vital for improving fire risk predictions and informing climate adaptation strategies to safeguard communities and ecosystems.”

“Understanding how climate factors influence wildfires is more critical than ever,” says Professor Lee. “Recognizing the increasing role of the Southern Annular Mode and the complex land-atmosphere interactions enables us to develop more accurate prediction models and better prepare for future wildfire seasons.”

The findings of this research were published in Agricultural and Forest Meteorology on April 11, 2026. This research was supported by the Korea Environment Industry & Technology Institute (KEITI) under the Climate Change R&D Project for New Climate Regime project, funded by the Ministry of Environment (MOE) of Korea. 

Journal Reference

Kiwook Kim, Myong-In Lee, Seungseok Lee, et al. , “Local and remote drivers of increased variability in extreme wildfire conditions in Southeastern Australia,” Agric. For. Meteorol., (2026).