Summer balance 2025: Ruhrverband reports significant lack of precipitation

The summer of 2025 was significantly too dry in the Ruhr catchment area. All three months had below-average precipitation. While July brought almost average precipitation, the deficits in June and especially in August were considerable. In total, it only rained 189 millimetres in summer 2025 - around a third less than the long-term average. Since 1927, there have only been twelve summers with even lower values, most recently in 2022 with 120 millimetres. It has been too dry since February: With the exception of April and July, all months were below the target. In the seven months from February to August, precipitation totalled just 360 millimetres - around 40 percent less than usual. 

Temperatures were also above average. At 17.3 °C, June was 2.0 degrees too warm - there have only been seven years with a hotter June since 1881. Overall, the summer of 2025 reached an average of 17.3 °C. This makes it the eighth warmest summer since weather records began in 1881. 

Since 1 July 2025, the Ruhrverband has been using the limits for the minimum discharge in the Ruhr, which were amended in December 2024, for the first time. The new regulations made it possible to save just over 15 million cubic metres of water in July and August - equivalent to 1.2 times the capacity of the Ennepetalsperre dam. Nevertheless, extensive water releases from the reservoirs were necessary in summer 2025: In Villigst on 81 days, at the mouth on 51 days - in each case around 50 per cent more than the average for the summers of 1991-2024. 

By the end of August, the reservoir levels had fallen to 72.8 per cent and were therefore slightly below the long-term average. However, with 343.7 million cubic metres of water, the reservoir system is still well positioned to both cope with further dry periods and contribute to flood protection.