The growing link between heatwaves and megafires: evidence from southern Mediterranean countries of Europe

The increasing trend of extreme wildfire events is concerning national agencies at multiple levels because of their potential impacts on ecosystem services and the capacities of emergency management systems. This concern is exacerbated by the increasing occurrence of heatwaves (HWs) which intensify the impacts of concomitant events. Thus, we wanted to assess recent trends on HWs and megafires and the spatial and temporal co-occurrence of these events. We focused on the most fire prone countries in Europe, i.e., Portugal, Spain, France, Italy and Greece, and considered varying fire size thresholds for defining megafires. Our analysis shows that HWs and megafires have increased during the last 16 years, especially those of greater size. Furthermore, the percentage of events occurring under a HW increases when increasing the threshold used for defining megafires. HW intensity emerges as a more important HW characteristic driving megafires occurrence than HW duration. The research’s temporal scope (2008–2023) provides a contemporary view of these relationships, capturing recent changes in both climate and fire regimes. However, it also raises questions about other important factors not captured in the analysis that might drive extreme wildfire occurrence.