Cheap flights from Ontario to St. Louis from C$ 264

The month of January is, on average, the cheapest month to fly to St. Louis from Region of Ontario, with most prices found around C$ 584. If you don’t want to visit St. Louis in January, then you should wait until February to fly from Region of Ontario, when ticket prices are also cheap, with an average price of C$ 597.

Our data shows that Tuesday is the least expensive day to fly to St. Louis. Tickets to fly out on this day can be as low as C$ 644. The most expensive day to fly to St. Louis is Monday, with ticket prices averaging around C$ 850.

The cheapest time of day to fly to St. Louis is in the morning when flights can be purchased for as low as C$ 672. If you have a flexible travel schedule, then try to avoid flying in the evening when prices are C$ 1,010 on average. Flights to St. Louis from Region of Ontario in the evening are generally more expensive because this time of day is more convenient for travellers’ schedules.

Fly from Toronto Pearson Intl to Lambert-St Louis for the best Ontario - Lambert-St Louis flight prices

You are more likely to see cheaper flights to St. Louis from Region of Ontario when booking weeks ahead of your departure date. In general, you can expect to find flights to St. Louis for around C$ 752 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to St. Louis from Region of Ontario for as low as C$ 417 on momondo.

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

The number of flights available between Region of Ontario and St. Louis is 2 per week as of November 2026. The most frequent departure day is Mon, with 100% of weekly flights leaving on this day.

Flight times vary depending on what airport in Region of Ontario you fly out of and what airport in St. Louis you fly into. For example, flying from Toronto to St. Louis takes 2h 16m on average. On the other hand, flying from Ottawa to St. Louis takes 8h 39m on average. Keep in mind that it’s always quicker to opt for a non-stop flight, so be sure to check momondo to see if there are any available for your route.