May in Downtown DC averages a daily high of 24.8°C with nights around 13.2°C. Expect roughly 12.6 wet days totalling 116.1mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Downtown DC is April–May.
Based on NATIONAL ARBORETUM DC, MD US (4.8km), 1995–2024. 29 years of May data.