$100 Cheap Delta flights St. Louis (STL) to Washington (IAD)

Grab cheap return Delta Air Lines flights from $180 from STL to IAD by filtering your results from “Price (lowest to highest)” on Expedia. Or look for bargains from $100 for a one-way trip.**These prices were available on Expedia within the past 7 days, for flights departing within the next year. Prices and availability are subject to change. Additional terms apply.

Delta Air Lines flights to Washington tend to be more affordable in the low-season months of January and February. Whether you’re after a one-way or round-trip ticket, you could score a better deal then.

Look for cheap Delta Air Lines flights from Lambert-St. Louis Intl. Airport (STL) to Washington Dulles Intl. Airport (IAD) one to three months prior to your day of departure. Travelers who book domestic flights 34 to 86 days in advance can save 25% compared to those who book just 6 to 12 days ahead. Regardless of fare type and itinerary, the ideal day to book a domestic flight is usually Sunday and the most expensive day tends to be Monday. Passengers who book on a Sunday can save 6% on average compared to those who book on a Monday.**Ideal booking window recommendation is based on average round-trip ticket prices for January through November for 2024. Best day of the week to book recommendation is based on average round-trip ticket prices for January through October 2024. All data sourced from ARC’s global airline sales database.

To find out if there’s a direct trip from STL to IAD with Delta Air Lines or other carriers, use our “Nonstop” filter when searching for flights.

Filter your results by “Early Morning” and “Morning” to browse the earliest departures from STL to IAD. Leaving early means you’re less likely to experience cancellations.**Most reliable time of the day recommendation is based on January through August 2024 flight status data sourced from OAG’s global flight data platform.

Board a Delta Air Lines flight from Lambert-St. Louis Intl. Airport (STL) to Washington, and you’re most likely to touch down at Washington Dulles Intl. Airport (IAD). This is the airline’s main hub in this city.

With an excellent in-flight experience and a rewarding loyalty program, Delta Air Lines is a popular option for many passengers flying from STL to IAD. What’s more, if you’re a Delta SkyMiles and One Key™ member booking with Expedia, you could earn OneKeyCash™* on eligible flights on top of your airline miles, which can be put toward future travel.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.

Depending on the type of ticket you purchased, a fee typically applies if you change or cancel your flight more than 24 hours after confirmation. To secure flexible fares, select our “Changes included” and “No cancel fee” boxes when you look for flights. For more information on modifying or canceling your reservation, go to “Trips,” select your flight and click on “Manage Booking.”