Cheap flights from St. Louis to Washington, D.C. from $72

The month of August is, on average, the cheapest month to fly to Washington, D.C. from St. Louis, with most prices found around $67. If you’re not able to fly to Washington, D.C. in August, then February is your next best option. Flight prices from St. Louis to Washington, D.C. during February average around $73.

On average, the least expensive day to fly to Washington, D.C. from St. Louis is on a Friday. momondo users have found tickets for Friday departures for as low as $382. However, this price may fluctuate depending on the airline, the season, and holidays. When flying out on a Sunday, the most expensive travel day of the week, you can expect to see flight prices from St. Louis to Washington, D.C. for around $488.

In the afternoon is the cheapest time of day to fly from St. Louis to Washington, D.C. when you can find flight prices for as low as $346. Flying to Washington, D.C. in the afternoon is an ideal time because this is during off-peak travel hours. Try not to purchase tickets at noon because they tend to be around $578. Of course, these prices can vary depending on the time of year and what airport you fly to.

Fly from Lambert-St Louis to Washington, D.C. Dulles Intl for the best Lambert-St Louis - Washington, D.C. flight prices

You are more likely to see cheaper flights to Washington, D.C. from St. Louis when booking weeks ahead of your departure date. In general, you can expect to find flights to Washington, D.C. for around $374 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Washington, D.C. from St. Louis for as low as $263 on momondo.

There are 4 cabin classes available to choose from on St. Louis to Washington, D.C. flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

You could potentially save up to 38% on your flight if you consider stops on a St. Louis to Washington, D.C. flight.

As of June 2026, prices for St. Louis to Washington, D.C. flights are approximately 14% cheaper when compared to flights at the same time last year.

Frontier, Southwest, and Delta are the most popular carriers operating from Lambert-St Louis to Washington, D.C.

Southwest, American Airlines and United Airlines are the top three most popular airlines that fly to Washington, D.C. from St. Louis according to our data. Southwest is the first choice among our users, with 55% of people opting to fly with this airline when traveling to Washington, D.C.. Keep in mind that there are 5 different airlines that fly to Washington, D.C. on a routine basis, so you have a few additional options to choose from.

The number of flights available between St. Louis and Washington, D.C. is 15 per day as of June 2026. The most frequent departure time is 8:00AM, with 49% of daily flights leaving at noon.

The number of flights available between St. Louis and Washington, D.C. is 106 per week as of June 2026. The most frequent departure day is Mon, with 19% of weekly flights leaving on this day.