December in Washington averages a daily high of 9.3°C with nights around 1.3°C. Expect roughly 9.8 wet days totalling 86mm. Demanding conditions — pack for it and plan indoor options.
Across the year, the best time to visit Washington is April–May.
Based on WASHINGTON REAGAN NATIONAL AIRPORT, VA US (5.3km), 1995–2024. 30 years of December data.