Fall weather brings the average daily temperatures in the range of a comfortable 63°F (17.2°C) to 79°F (26.1°C). September is one of the best intervals to visit Washington, D.C., with fewer crowds compared to spring and summer due to the end of the school breaks. There are fewer lines to stand in, and more time to enjoy the tours in the lovely autumn. Be sure to pack some warm clothes to protect from an odd cold bout or two. The Library of Congress National Book Festival during September is also an entertaining way to pass rainy fall afternoons.