April to May and September to October. Month by month below, with the weather, what's on and what it costs to fly there from your city.
Sources agree spring and fall are best for weather; April has cherry blossoms but the biggest crowds, and May, September and October are calmer.
3 of the 5 travel guides we read name these months.
Average high and low in Washington, and days with rain
JanuaryChecking fares…Average high 43F; probably the slowest month for tourism.Coldest month with the lowest crowds, short daylight and snow potential.Martin Luther King Jr. Day brings some museum crowds.
FebruaryChecking fares…Same as January: cold and slow for tourism.Low to moderate crowds, with Valentine's week and Presidents' Day weekend upticks; early cherry blossoms possible in mild winters.
MarchChecking fares…Highs around 55F, with more tourists late in the month as cherry blossoms near peak.The cherry blossoms peak between the second half of March and mid-April.National cherry blossom festival
Best timeAprilChecking fares…Highs average 66F; blossoms peak by mid-month and the Mall is very crowded on peak weekends.The National Cherry Blossom Festival in March and April draws over 1.5 million visitors.One guide calls April peak crowds and peak prices, and suggests late March or May for smaller crowds.
Best timeMayChecking fares…Sunny days, relatively low humidity, highs near 75F; the peak month for school groups.Late spring with warm pleasant weather and moderate crowds.National Memorial Day Parade
JuneChecking fares…Highs near 84F; hot and humid weather possible late in the month; school groups in the first two weeks.The Smithsonian Folklife Festival runs for two weeks around the Fourth of July.
JulyChecking fares…Hot and humid, average high 88F with days above 90F common; no school groups but more families.Hottest and rainiest month.Independence Day is one of the most crowded days; the metro is advised.Independence Day on the National Mall
Best timeSeptemberChecking fares…Average high 79F, nice weather, not as crowded as spring.The H Street Festival takes over 11 blocks each September.
Best timeOctoberChecking fares…Average high 68F; leaves peak near the third week.Generally nice weather and a good time to visit.
NovemberChecking fares…Average high 57F, mild and not crowded except Thanksgiving week.The Downtown Holiday Market opens in November and December.National Christmas Tree Lighting
DecemberChecking fares…Highs of 46F; bitterly cold weather and snow is uncommon. Not crowded except the week between Christmas and New Year's.City lit up for the holidays.Weather: Washington averages from NOAA (1961 to 1990 averages), as listed in its climate table on Wikipedia.
Live fares from your airport. Watch them and we alert you when they drop.
Festivals and seasons through the year
Cancún
The Grand Canyon
Disneyland
Miami
Myrtle Beach
Prague
Bali
Maui
Montreal
Venice
Aruba
New Orleans
Nashville
Disney World
New York
Rome
San Diego
Phuket
Boston
Dubai
Seoul
Florida
Lisbon
Los Angeles
Chicago
Paris
Las Vegas
San Francisco
Edinburgh
Napa
Sydney
Hawaii
Scotland
Punta Cana
Savannah
Mexico City
Zion National Park
Turks and Caicos
Puerto Vallarta
Honolulu
Banff
Yosemite
Tulum
The Bahamas
Sedona
Seattle
Santorini
Buenos Aires
London
Charleston
Rio de Janeiro
Palm Springs
Yellowstone
Amsterdam
Toronto
Key West
Orlando
Europe
Austin
Machu Picchu
Cabo San Lucas
Niagara Falls
Colorado
Oregon
Arizona
Acadia National Park
Galapagos
Lake Tahoe
Montana
Kauai
Okinawa
US Virgin Islands
Amalfi Coast
Santa Fe
Destin
Curacao
Utah
Joshua Tree
Patagonia
St. Thomas
Florida Keys
Smoky Mountains
Copenhagen
Death Valley
Mallorca
Madeira
Cape Town
Ibiza
Zanzibar
Lake Como
Madrid
New Mexico
Tennessee
Vermont
Wyoming
Bryce Canyon
Oahu
St. Martin
Hilton Head
Dolomites
Cape Cod
San Antonio
Rocky Mountain National Park
Dublin
Catalina Island
Athens
Asheville
Texas
South America
Shenandoah National Park
Phoenix
North Carolina
Medellín
Cairo
Budapest
Arches National Park
St. John
South Carolina
Reykjavik
Mykonos
Milan
Houston
Hanoi
Canary Islands
Big Island of Hawaii
Atlanta
The Caribbean
St. Barts
South Dakota
Rhode Island
New England
Nassau
Lima
Kyoto
Koh Samui
Colorado Springs
Chiang Mai
Stockholm
Porto
Montego Bay
Michigan
Melbourne
Louisiana
Kuala Lumpur
Kruger National Park
Jeju
Florence
Dallas
Zurich
Tampa
St. Kitts
Osaka
Munich
Moorea
Kailua-Kona
Everglades
Door County
Cusco
Calgary
Boracay
Bonaire
Swiss Alps
St. Croix
Seville
San Juan Islands
New Hampshire
Minnesota
Mazatlán
Manila
Kentucky
Isla Mujeres
Guam
French Riviera
Fort Lauderdale
Cinque Terre
Asia
Algarve
Virginia
Tenerife
Sapporo
Nairobi
Mumbai
The Hamptons
Grand Teton National Park
Finger Lakes
Charlotte
Bogotá
Auckland
Maine
Bora Bora
Olympic National Park
Redwood National Park
Sequoia National Park
Big Bend National Park
Mackinac Island
Sint Maarten
Nantucket
Outer Banks
California
Big Sur
Crater Lake
Scottsdale
Nice
Mount Rainier
Cozumel
Badlands National Park
Salt Lake City
Denali
Philadelphia
Tucson
Provence
Guadalajara
Albuquerque
Upper Peninsula
Sonoma
Memphis
Idaho
Da Nang
Cotswolds
Arkansas
St. Louis
Capri
Glacier National Park
Barcelona
Vancouver
Denver
Istanbul
Riviera Maya
Carmel-by-the-Sea
Santiago, Chile
Naples, Italy
Central America
Minneapolis
Sarasota
Halifax, Nova Scotia
Pittsburgh
Helsinki
Pensacola
Johannesburg
Brisbane
Málaga
Phu Quoc
Perth
Dubrovnik
Corpus Christi
Massachusetts
Oklahoma
Torres del Paine
Czech Republic
Ho Chi Minh City
Anchorage
Boise
Louisville
Juneau
Quito
West Virginia
Wisconsin
Canyonlands National Park
Baja California
Blue Ridge Mountains
Fort Myers
Detroit
Kansas City, Missouri
Kathmandu
Reno
Cebu
Brussels
Guangzhou
Chattanooga
Antalya
Daytona Beach
Cairns
Hilo
Alabama
Connecticut
New Jersey
Pennsylvania
Capitol Reef National Park