Cheap flights from Boston to St. Louis from $71

In general, August is the cheapest month to fly from Boston to St. Louis. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $382. The month of September is another great option to travel to St. Louis, with average flight prices from Boston averaging around $400.

The cheapest day to depart on your flight to St. Louis is on a Wednesday when prices can be found for as low as $421. 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 $486. 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 Boston in the evening is the least expensive time of day to depart. momondo users have found prices as low as $424 when looking at flights departing in the evening. At noon is when there is more demand to fly to St. Louis, so prices are often more expensive at around $468 per ticket.

Fly from Boston Logan Intl to Lambert-St Louis for the best Boston Logan Intl - Lambert-St Louis flight prices

You are more likely to see cheaper flights to St. Louis from Boston when booking weeks ahead of your departure date. In general, you can expect to find flights to St. Louis for around $457 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to St. Louis from Boston for as low as $386 on momondo.

There are 3 cabin classes available to choose from on Boston Logan Intl 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.

United Airlines, Southwest, and Delta are the most popular carriers operating from Boston Logan Intl to Lambert-St Louis

American Airlines, Southwest and Delta are the top three most popular airlines that fly to St. Louis from Boston according to our data. American Airlines 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 7 different airlines that fly to St. Louis on a routine basis, so you have a few additional options to choose from.

Historically, on average around 18% of flights between Boston and St. Louis have experienced a delay on any given week. The average delay length over the past 12 months has been 140 minutes.

Generally, flights departing at night tend to experience fewer delays. Flights in the evening have, in the past, seen delays more frequently in comparison.

Saturday is statistically the day of the week which experiences the fewest number of delays on this flight route. Sunday has historically seen more delays on average compared to the rest of the week.

According to our data, American Airlines have had the least number of delays on this route over the last 12 months; with about 12% of their flights experiencing any sort of delay.

As of March 2026, there are 3 flights per day flying from Boston to St. Louis. The most common time of day flights depart is 5:00AM, with 29% of flights taking off in the morning.

21 flights are operational weekly from Boston to St. Louis as of March 2026. The most popular departure day for this route is Mon, with 19% of flights per week taking off on this day.