Washington’s summers are blisteringly hot and humid, so plan on visiting in spring and fall when temperatures remain mild and the school-vacation crowds are at their ebb. Each spring, the National Cherry Blossom Festival typically signals the start of “tourist season,” though that can also be when the weather is most fickle—sunny and mid-60s one day, rain and wind the next (read: Pack layers). Lots of people come to town for the festival, and there’s no guarantee the blossoms will actually be out, but catch it right and you’ll be rewarded with one of the most beautiful spectacles in city travel.
Heat and humidity aside, summer can work if you’re strategic about where you visit. Hit the star attractions first thing in the morning to avoid waiting in line in the sun, and save those off-the-beaten-path spots (hopefully ones with air conditioning) for later in the day. Visit the monuments at dusk for stellar sunset photo ops. Surprisingly, summer hotel rates can be competitive because many of the politicians, businessfolk, and convention-goers aren’t in town.
Fall is ideal, though it doesn’t start for real until October most years and can be fleeting, with chilly northerly winds heralding several months of biting sub-zero days, particularly in January and February. Winter brings subfreezing temperatures and occasional ice, though snow is more rare here than in Northeastern cities.