April in Köln averages a daily high of 16.1°C with nights around 6.7°C. Expect roughly 11.1 wet days totalling 49.1mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Köln is May–September.
Based on KOLN STAMMHEIM, GM (6.7km), 1995–2024. 29 years of April data.