Cheap flights from Portland to St. Louis from $80

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 Wednesday when prices can be found for as low as $249. 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 $532. 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 $365 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 $679 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 $369 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 $263 on momondo.

You could potentially save up to 6% on your flight if you consider stops on a Portland to St. Louis flight.

As of May 2026, prices for Portland to St. Louis flights are approximately 54% more expensive when compared to flights at the same time last year.

Alaska Airlines and Delta are the most popular carriers operating from Portland to Lambert-St Louis

Delta, United Airlines and Southwest 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 38% 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: 75% 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 48m.

Denver (DEN) has the shortest average layover time for this route: 1h 09m.