Seasonality of Heatwaves in Central Europe: Insights from Dynamical Systems Theory and Weather Regimes

Heat extremes have severe impacts on human health, economies, and ecosystems. In particular in Europe, heatwaves are expected to become more frequent and intense with climate change, making it essential to understand and quantify the key factors driving these events, such as soil moisture deficits and atmospheric circulation. Further, global warming is likely not only to increase the frequency and intensity of heatwaves in the summer, but also in early autumn, highlighting the need to explore seasonal variations in their drivers.

We analyze heatwaves in Central Europe (45–55°N, 4–16°E) in the historical period (1950-2023) by quantifying atmospheric persistence and exploring the link between surface temperatures and atmospheric circulation patterns using dynamical system theory. This approach is further contextualized by an analysis of weather regimes representing the low-frequency variability of the atmosphere over the North Atlantic and Europe. Using ERA5 reanalysis data, we examine intra-seasonal variations of heatwaves during the extended summer months (May–September). Our results show an anomalously strong link between atmospheric circulation and surface temperatures on heatwave days. In July and August, an anomalously high persistence of the atmospheric circulation is found on heatwave days, associated with an enhanced frequency of Scandinavian and European blocking weather regimes. Moreover, we investigate additional drivers of heatwaves such as soil moisture, and examine the life cycle of heatwaves.