Cheap flights from St. Louis to Pennsylvania from $70

The month of August is, on average, the cheapest month to fly to Pennsylvania from St. Louis, with most prices found around $277. If you don’t want to visit Pennsylvania in August, then you should wait until September to fly from St. Louis, when ticket prices are also cheap, with an average price of $340.

The cheapest day to depart on your flight to Pennsylvania is on a Friday when prices can be found for as low as $580. 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 Saturday because tickets tend to average around $970. These prices are subject to change though, so be sure to set up a Price Alert for flights to Pennsylvania.

Our most recent data shows that the best time of day to fly to Pennsylvania is in the evening. Flights from St. Louis to Pennsylvania during this time can be as low as $423. In contrast, the most expensive time of day to depart to Pennsylvania is at noon when prices are around $1,075.

Fly from Lambert-St Louis to Philadelphia for the best Lambert-St Louis - Pennsylvania flight prices

You are more likely to see cheaper flights to Pennsylvania from St. Louis when booking weeks ahead of your departure date. In general, you can expect to find flights to Pennsylvania for around $407 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Pennsylvania from St. Louis for as low as $331 on momondo.

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

Frontier, Southwest, and United Airlines are the most popular carriers operating from Lambert-St Louis to Pennsylvania

American Airlines, Southwest and Frontier are the top three most popular airlines that fly to Pennsylvania from St. Louis according to our data. American Airlines is the first choice among our users, with 57% of people opting to fly with this airline when traveling to Pennsylvania. Keep in mind that there are 6 different airlines that fly to Pennsylvania on a routine basis, so you have a few additional options to choose from.

The number of flights available between St. Louis and Pennsylvania is 30 per day as of April 2026. The most frequent departure time is 2:00PM, with 55% of daily flights leaving in the afternoon.

As of April 2026, 211 flights take off from St. Louis and land in Pennsylvania each week. The most common flight departure day for this route is Thu, with 21% of weekly flights taking off on this day.