May in Rockville averages a daily high of 24.8°C with nights around 12.3°C. Expect roughly 11.6 wet days totalling 115.3mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Rockville is April–May.
Based on DALECARLIA RESERVOIR, MD US (16.5km), 1995–2024. 26 years of May data.