Emerging Links between Droughts, Heatwaves and Extreme Precipitation in a Western Mediterranean Hotspot: Evidence of Intensifying Compound and Sequential Hazards

Abstract Extreme climate hazards can occur in isolation or interact as concurrent or compound events, amplifying their impacts. In the Mediterranean basin these interactions pose significant risks and result in catastrophic socio-economic impacts. This study analyzes the occurrence and impacts of compound and sequential climate events—heatwaves, droughts, forest fires, and extreme precipitation—in the Western Mediterranean Valencian Community, a climate change hotspot. Using daily data from 1979 to 2021, we identify atmospheric heatwaves, droughts, and extreme precipitation events with a high-resolution gridded observational dataset, analyze wind conditions and assess marine heatwaves using regional reanalysis. Forest fire occurrences are examined through vectorial data. Our results reveal a rising frequency of 2.2 concurrent hazard days per decade, with droughts emerging as a key driver of summer wildfires and commonly preceding extreme autumn precipitation. Notably, our analysis of Normalized Information Flow (NIF) highlights the increasing influence up to 12% of Mediterranean Sea warming on extreme autumn precipitation in delimited areas at p-value < 0.05. This finding suggests an increasing influence of marine heatwaves on autumnal flood risks, marking the emergence of new climate hotspots in the region. This study provides novel insights into the sequential effects of compound climate hazards, highlighting the growing interconnections between droughts, heatwaves, and precipitation extremes. Understanding these linkages is critical for strengthening early-warning systems and developing adaptive strategies—such as improved fire management and coastal-flood preparedness—to reduce and mitigate impacts in Mediterranean climate hotspots. Graphical Abstract