The frequency of heavy rainfall events varies greatly from year to year. A link between the occurrence of heavy rainfall events in Germany and climate change is therefore possible, but cannot be determined from observations alone [1]. At the global level, the Intergovernmental Panel on Climate Change (IPCC) assumes an increase in heavy precipitation over land areas. This assumes more frequent and more intense precipitation. [2].

In the ClimXtreme consortium, this correlation was investigated by Hundhausen et al. (2024), among others. They found an increase in intensity of 6 to 8.5% per degree of global warming for Germany, with rare and short-lived events showing the strongest trends [3].

The heavy precipitation that led to flooding in Western Europe in July 2021, particularly in the Ahr region, was investigated using probabilistic attribution methodology. Tradowsky et al. attribute an increase in the intensity of maximum daily precipitation of 3 to 19% and an increase in probability by a factor of 1.2 to 9 for the affected region to climate change [4].

For hail, another form of precipitation besides rain, the data available to date is insufficient to establish a clear link with climate change. However, initial analyses indicate a negative trend in hail frequency in large parts of Germany and a positive trend in southern Germany [5].

Voit et al. (2025) propose a new approach for more robustly determining peak discharges of flash floods with long return periods. To this end, they use historical heavy precipitation events that occurred in the vicinity of the catchment area under investigation. In this way, they extend conventional extreme value statistics for isolated catchments [6].

Bürger and Heistermann (2026) use a novel downscaling approach to investigate historical and future changes in heavy rainfall events in Germany. They find that large-scale factors promoting convective heavy precipitation are increasing, as are factors that inhibit it. This leads to a high degree of uncertainty in the assessment, even though their analysis confirms an increase in extreme precipitation in Germany [7].

For specific questions, please feel free to contact the research groups using the contact information provided. For general questions, please send an email to info@climxtreme.de.