Cheap flights from Ontario to St. Louis from $187

In general, December is the cheapest month to fly from Region of Ontario to St. Louis. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $168. The month of October is another great option to travel to St. Louis, with average flight prices from Region of Ontario averaging around $175.

The cheapest day to depart on your flight to St. Louis is on a Sunday when prices can be found for as low as $394. 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 $548. 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 Region of Ontario in the afternoon is the least expensive time of day to depart. momondo users have found prices as low as $405 when looking at flights departing in the afternoon. In the evening is when there is more demand to fly to St. Louis, so prices are often more expensive at around $584 per ticket.

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 $521 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 $359 on momondo.

There are 2 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.

As of June 2026, 6 flights take off from Region of Ontario and land in St. Louis each day. The most common flight departure time for this route is 11:00AM, with 50% of daily flights taking off at noon.

The number of flights available between Region of Ontario and St. Louis is 42 per week as of June 2026. The most frequent departure day is Mon, with 14% of weekly flights leaving on this day.