Cheap flights from Washington, D.C. to St. Louis from $71

In general, October is the cheapest month to fly from Washington, D.C. to St. Louis. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $72. The month of December is another great option to travel to St. Louis, with average flight prices from Washington, D.C. averaging around $78.

The cheapest day to depart on your flight to St. Louis is on a Wednesday when prices can be found for as low as $351. This is often the case because there is less demand to fly during this day of the week. If your travel schedule is flexible, try to avoid departing on a Sunday because tickets tend to average around $434. These prices are subject to change though, so be sure to set up a Price Alert for flights to St. Louis.

Flying to St. Louis from Washington, D.C. at noon is the least expensive time of day to depart. momondo users have found prices as low as $350 when looking at flights departing at noon. In the afternoon is when there is more demand to fly to St. Louis, so prices are often more expensive at around $401 per ticket.

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

You are more likely to see cheaper flights to St. Louis from Washington, D.C. when booking weeks ahead of your departure date. In general, you can expect to find flights to St. Louis for around $427 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to St. Louis from Washington, D.C. for as low as $124 on momondo.

There are 4 cabin classes available to choose from on Washington, D.C. to St. Louis 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 4% on your flight if you consider stops on a Washington, D.C. to St. Louis flight.

As of June 2026, prices for Washington, D.C. to St. Louis flights are approximately 25% more expensive when compared to flights at the same time last year.

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

Southwest, American Airlines and Frontier are the top three most popular airlines that fly to St. Louis from Washington, D.C. according to our data. Southwest is the first choice among our users, with 48% of people opting to fly with this airline when traveling to St. Louis. Keep in mind that there are 5 different airlines that fly to St. Louis on a routine basis, so you have a few additional options to choose from.

As of June 2026, 16 flights take off from Washington, D.C. and land in St. Louis each day. The most common flight departure time for this route is 5:00PM, with 49% of daily flights taking off in the afternoon.

As of June 2026, there are 117 flights per week flying from Washington, D.C. to St. Louis. The most common day of the week flights depart is Mon, with 18% of flights taking off on this day.