Forest fire risk in Croatia under a changing climate

Abstract. Forest fires in Croatia inflict substantial economic and ecological damage and frequently pose a threat to infrastructure and human lives. The southern part of the Croatian Adriatic, belonging to the Mediterranean basin, is the most severely affected region. To evaluate fire risk, the Canadian Fire Weather system was applied, and indices based on Fire Weather Index (FWI) – Seasonal Severity Rating (SSR), the number of days with FWI > 30 (FWI30), the 90-th percentile of FWI (FWIp90), and Length of Fire Season (LOFS) were derived. This study investigates the extent to which climate change has influenced the variability of latter indices across Croatia during June-September season. The analysis covers the period 1961–2020, revealing upward trends and predominantly positive anomalies in the evaluated indices. The most favourable fire weather conditions occur in the southern part of the Croatian Adriatic, which also exhibits the strongest increasing trends in SSR and FWI30. Although the continental parts of Croatia have historically been less susceptible to wildfires, the observed trends in the analysed indices suggest that conditions conducive to ignition and spread of wildfires are gradually emerging in these areas as well.