May in Koblenz averages a daily high of 18.5°C with nights around 7.2°C. Expect roughly 13.1 wet days totalling 73.1mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Koblenz is June–September.
Based on MONTABAUR, GM (18.7km), 1995–2024. 17 years of May data.