August in Downtown DC averages a daily high of 31.4°C with nights around 20.2°C. Expect roughly 9.9 wet days totalling 99.8mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Downtown DC is April–May.
Based on NATIONAL ARBORETUM DC, MD US (4.8km), 1995–2024. 26 years of August data.