May in Haarlem averages a daily high of 17.9°C with nights around 8.7°C. Expect roughly 12 wet days totalling 60mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Haarlem is May–September.
Based on SCHIPHOL, NL (12.7km), 1995–2024. 30 years of May data.