Cheap flights from Washington, D.C. Reagan-National Airport to St. Louis from $64

In general, August is the cheapest month to fly from Washington, D.C. Reagan-National Airport to St. Louis. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $267. The month of October is another great option to travel to St. Louis, with average flight prices from Washington, D.C. Reagan-National Airport averaging around $284.

The cheapest day to depart on your flight to St. Louis is on a Saturday when prices can be found for as low as $332. 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 $403. 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. Reagan-National Airport in the evening is the least expensive time of day to depart. momondo users have found prices as low as $308 when looking at flights departing in the evening. In the afternoon is when there is more demand to fly to St. Louis, so prices are often more expensive at around $377 per ticket.

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

You are more likely to see cheaper flights to St. Louis from Washington, D.C. Reagan-National Airport when booking weeks ahead of your departure date. In general, you can expect to find flights to St. Louis for around $337 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. Reagan-National Airport for as low as $219 on momondo.

There are 3 cabin classes available to choose from on Washington, D.C. Reagan-National to Lambert-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 22% on your flight if you consider stops on a Washington, D.C. Reagan-National Airport to St. Louis flight.

As of February 2026, prices for Washington, D.C. Reagan-National Airport to St. Louis flights are approximately 66% more expensive when compared to flights at the same time last year.

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

Southwest, American Airlines and Delta are the top three most popular airlines that fly to St. Louis from Washington, D.C. Reagan-National Airport according to our data. Southwest is the first choice among our users, with 54% of people opting to fly with this airline when traveling to St. Louis. Keep in mind that there are 3 different airlines that fly to St. Louis on a routine basis, so you have a few additional options to choose from.

3 flights are operational daily from Washington, D.C. Reagan-National Airport to St. Louis as of February 2026. The most popular departure time for this route is 3:00PM, with 40% of flights per day taking off in the afternoon.

25 flights are operational weekly from Washington, D.C. Reagan-National Airport to St. Louis as of February 2026. The most popular departure day for this route is Mon, with 28% of flights per week taking off on this day.