What is it? The cherry blossom trees that ring the Tidal Basin were gifted to the U.S. by Japan as a sign of goodwill and inter-country friendship. First celebrated in 1935, the National Cherry Blossom Festival (March 20-April 13), celebrates the change of seasons and the beauty of the city's iconic flowers. The festival itself includes lots of fun activities, like the beloved Blossom Kite Festival (March 29) near the Washington Monument and the parade (April 12).
Why go? Spring doesn't start in D.C. until the cherry blossoms bloom (peak bloom, when the flowers are at their most beautiful, is projected to happen from March 28-31). Cherry blossom season is akin to the holiday season in D.C.; local businesses get in on the action with themed drinks, food, and activities—the city even wraps Metro cars and buses in cherry blossom banners.
Time Out tip: The Tidal Basin gets absurdly crowded during cherry blossom season, so try to time your visit wisely. Weekends are always more crowded, so try to visit on a weekday. If you visit close to sunrise or closer to dusk, you'll get a sunrise or sunset view as a treat (and much smaller crowds).