Cheap flights from Ontario to St. Louis from $99

In general, April is the cheapest month to fly from Ontario to St. Louis. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $250. The month of November is another great option to travel to St. Louis, with average flight prices from Ontario averaging around $258.

The cheapest day to depart on your flight to St. Louis is on a Tuesday when prices can be found for as low as $426. 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 $624. 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 Ontario in the evening is the least expensive time of day to depart. momondo users have found prices as low as $437 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 $582 per ticket.

Frontier and Delta are the most popular carriers operating from Ontario to Lambert-St Louis

Southwest, American Airlines and Frontier are the top three most popular airlines that fly to St. Louis from Ontario according to our data. Southwest is the first choice among our users, with 55% 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.

Phoenix (PHX) was the most common stop: 67% of momondo users choosing 1-stop flights on this route connected there.

Flights via Denver (DEN) offer the lowest average round-trip price of $165.

Flights connecting via Phoenix (PHX) have the shortest average one-way travel time: 5h 07m.

Phoenix (PHX) has the shortest average layover time for this route: 0h 56m.