section_path: Geography/Climate
section_name: Climate
paragraph_text: Climate
  
  Washington's climate is temperate humid subtropical (Köppen: Cfa). Winters are cool to cold with some snow of varying intensity, while summers are hot and humid. The district is in plant hardiness zone 8a near downtown, and zone 7b elsewhere in the city.
  
  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. Heat indices regularly approach 100 °F (38 °C) at the height of summer. The combination of heat and humidity in the summer brings very frequent thunderstorms, some of which occasionally produce tornadoes in the area.
  
  Blizzards affect Washington once every four to six years on average. The most violent storms, known as nor'easters, often impact large regions of the East Coast. From January 27 to 28, 1922, the city officially received 28 inches (71 cm) of snowfall, the largest snowstorm since official measurements began in 1885. According to notes kept at the time, the city received between 30 and 36 inches (76 and 91 cm) from a snowstorm in January 1772.
  
  Hurricanes or their remnants occasionally impact the area in late summer and early fall. However, they usually are weak by the time they reach Washington, partly due to the city's inland location. Flooding of the Potomac River, however, caused by a combination of high tide, storm surge, and runoff, has been known to cause extensive property damage in the Georgetown neighborhood of the city. Precipitation occurs throughout the year.
  
  The highest recorded temperature was 106 °F (41 °C) on August 6, 1918, and on July 20, 1930. The lowest recorded temperature was −15 °F (−26 °C) on February 11, 1899, right before the Great Blizzard of 1899. During a typical year, the city averages about 37 days at or above 90 °F (32 °C) and 64 nights at or below the freezing mark (32 °F or 0 °C). On average, the first day with a minimum at or below freezing is November 18 and the last day is March 27.