May in Altona averages a daily high of 18.7°C with nights around 8.5°C. Expect roughly 13.3 wet days totalling 59.5mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Altona is May–September.
Based on HAMBURG NEUWIEDENTHAL, GM (8.2km), 1995–2024. 30 years of May data.