Cheap flights from Portland to St. Louis from $92

In general, November is the cheapest month to fly from Portland to St. Louis. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $300. The month of September is another great option to travel to St. Louis, with average flight prices from Portland averaging around $318.

The cheapest day to depart on your flight to St. Louis is on a Friday when prices can be found for as low as $213. 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 $621. 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 Portland in the morning is the least expensive time of day to depart. momondo users have found prices as low as $366 when looking at flights departing in the morning. At noon is when there is more demand to fly to St. Louis, so prices are often more expensive at around $645 per ticket.

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

You are more likely to see cheaper flights to St. Louis from Portland when booking weeks ahead of your departure date. In general, you can expect to find flights to St. Louis for around $361 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to St. Louis from Portland for as low as $222 on momondo.

There is only 1 cabin class available to choose from on Portland 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 5% on your flight if you consider stops on a Portland to St. Louis flight.

As of March 2026, prices for Portland to St. Louis flights are approximately 10% cheaper when compared to flights at the same time last year.

Frontier is the most popular carrier operating from Portland to Lambert-St Louis

Delta, Southwest and United Airlines are the top three most popular airlines that fly to St. Louis from Portland according to our data. Delta is the first choice among our users, with 36% of people opting to fly with this airline when traveling to St. Louis. Keep in mind that there are 6 different airlines that fly to St. Louis on a routine basis, so you have a few additional options to choose from.

Denver (DEN) was the most common stop: 50% of momondo users choosing 1-stop flights on this route connected there.

Flights via Minneapolis (MSP) offer the lowest average round-trip price of $249.

Flights connecting via Denver (DEN) have the shortest average one-way travel time: 5h 39m.

Salt Lake City (SLC) has the shortest average layover time for this route: 1h 03m.