Washington, DC, has a humid subtropical climate. Temperatures vary greatly in Washington, DC, throughout the year, as the city sees four distinct seasons. On average, the warmest month of the year is July, when the average high temperature is 89 degrees and the average low temperature is 71 degrees. By contrast, the coldest month is January, when the average high temperature is only 43 degrees, and the average daily low temperature reaches 29 degrees. In the spring and autumn months, temperatures are regularly in the 50s and 60s.
Washington, DC, sees the most precipitation in the month of May, when the average rainfall reaches almost 4 inches. The least amount of precipitation is in January and February, when the city only sees an average of 2.8 and 2.7 inches, respectively. Most other months see an average of between 3 and 3.5 inches of precipitation, which can include both rainfall and snowfall.
Washington, DC, sees more sunny days than cloudy ones. The average number of days per year with sun is 202, which is just under the national average of 205 days. Naturally, the most sun occurs during the summer months when there is less precipitation and longer daylight hours. June has the most hours of sunlight on average, with just over 282 hours of sunlight each year.
Washington, DC, has the highest wind speeds between December and April, when the average wind knots reaches 11. In the summer, the wind speed averages only 6 knots. The city sees an overall wind speed average of 9 knots throughout the year. The wind's direction in Washington, DC also changes based on the season. Between May and October, wind comes from the south, and the rest of the year the wind's direction is from the northwest.
The level of humidity, or water vapor in the air, is at its highest in Washington, DC during the early morning hours between August and October. During this time period, the percentage of relative humidity is nearly 90%. Generally, the humidity is always 20 to 30 percentage points higher at 7 am than it is in the afternoon at 4 pm. Humidity averages at its lowest in Washington, DC during the afternoon between February and May, when the percentage of relative humidity averages just under 50%.