Berlin: According to Andreas Marx, who oversees the drought index at the Helmholtz Centre for Environmental Research, the worsening situation is not being driven solely by the recent heat wave. Instead, it is the result of an extended rainfall deficit that has stretched over the past eight months.

Marx said the heat wave has accelerated the drying of the topsoil, particularly the upper 25 centimetres, and in some areas as deep as 30 to 40 centimetres. Rising temperatures have increased evaporation while also raising the amount of water consumed by plants.

“Wherever there is water in the upper layers, it is lost relatively quickly,” he said.

The drought has also affected deeper soil layers and groundwater reserves. While deeper soils can normally absorb rainfall over the course of a year, low rainfall since the autumn of 2025 has left groundwater levels under strain.

Drought index maps measuring soil moisture at depths of around 1.8 metres in Germany’s far south have turned dark red, signalling exceptional drought conditions.

Marx warned that the deficit is unlikely to ease during the summer, when soils typically become even drier. He said the current moisture levels would require an exceptionally wet summer to recover — a scenario he described as unlikely.

The situation is placing additional pressure on forests, increasing the risk of drought-related damage and indirect threats such as bark beetle infestations.

Low groundwater levels could also trigger further declines in river water levels, which are already under pressure. A significant share of river flow comes from groundwater, Marx noted, raising concerns over possible economic disruption if low water levels prevent cargo vessels from operating at full capacity.