May in Gronau averages a daily high of 18.8°C with nights around 6.9°C. Expect roughly 12.2 wet days totalling 60.1mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Gronau is May–September.
Based on TWENTHE, NL (11.3km), 1995–2024. 30 years of May data.