Cheap flights from Ontario to St. Louis from $108

In general, September 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 $249. The month of April is another great option to travel to St. Louis, with average flight prices from Ontario averaging around $250.

The cheapest day to depart on your flight to St. Louis is on a Thursday when prices can be found for as low as $405. 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 Monday because tickets tend to average around $549. 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 $331 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 $556 per ticket.

You are more likely to see cheaper flights to St. Louis from Ontario when booking weeks ahead of your departure date. In general, you can expect to find flights to St. Louis for around $333 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to St. Louis from Ontario for as low as $328 on momondo.

Frontier is the most popular carrier 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 51% 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.