March in Downtown DC averages a daily high of 13.7°C with nights around 2.1°C. Expect roughly 9.6 wet days totalling 90.2mm. 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. 28 years of March data.