Washington is in the northern part of the humid subtropical climate zone (Köppen: Cfa) However, under the Trewartha climate classification, the city has a temperate maritime climate. Winters are usually chilly with light snow, and summers are hot and humid. The District is in plant hardiness zone 8a near downtown, and zone 7b elsewhere in the city, indicating a humid subtropical climate. 

Spring and fall are mild to warm, while winter is chilly with annual snowfall averaging 15.5 inches (39 cm). Winter temperatures average around 38 °F (3.3 °C) from mid-December to mid-February. Summers are hot and humid with a July daily average of 79.8 °F (26.6 °C) and average daily relative humidity around 66%, which can cause moderate personal discomfort. The combination of heat and humidity in the summer brings very frequent thunderstorms, some of which occasionally produce tornadoes in the area.