Book low fares from Ontario/LA to St. Louis with Southwest Airlines®. It’s easy to find the Ontario International Airport to Lambert-St. Louis International Airport flight to make your booking and travel a breeze. Whether you’re traveling for business or pleasure, solo or with the whole family, you’ll enjoy flying Southwest®. Have flexible travel dates? Plug them into the Low Fare Calendar and see the lowest fares available within your travel window. You may also want to browse Southwest Vacations® to see special offers and package deals on flights, hotels, rental cars, and more.
Explore your options and book your Ontario/LA to St. Louis flight with Southwest today!
Best Airline in the U.S. and North America & Best Economy and Low Cost Airline in North America.
Ontario/LA, CA to St. Louis, MO
*Restrictions and exclusions apply. Seats and dates are limited. Select markets. 21 travel days available.
Middle seats open through November 30
Full exchange of fresh, outdoor air every 2-3 minutes while inflight
Face coverings required
Departing from: Ontario International Airport (ONT)
Arriving at: Lambert-St. Louis International Airport (STL)
Daily flights
Weekly flights
Flightsbefore noon
Flightsbetween
12-6pm
Other popular flights from Ontario/LA
View our interactive map†Based on DOT published scheduled average flights Monday-Friday between 10/9/2020 and 12/31/2020, as of 10/9/2020.
One child over 14 days and under two (2) years of age, not occupying a seat, may be carried free of charge when traveling with an adult (12 years of age or older). Learn more.
Customers flying with a pet are subject to a pet fare. To learn more about traveling with your furry friend, explore the Southwest® pet policy.
Minors under the age of 18 are not permitted to fly unaccompanied on international flights or any itinerary that includes an international flight. Learn more.
Start packing! Every ticketed Customer’s first two checked bags are free. Learn more.
Lambert-St. Louis International Airport will bring you within 14 miles of downtown St. Louis. Hop on a bus, or train, or call a car to get on your way.
At Southwest, we know it takes more than great deals on St. Louis airfares and convenient scheduling options to make your trip memorable. So from booking to boarding, we offer services and features designed to make your travel from Ontario/LA to St. Louis the best it can be. Find out more about the Southwest® Experience before you book your Ontario International Airport to Lambert-St. Louis International Airport flight.
Flying with Southwest is simple and fun, no matter which of our dozens of exciting destinations you choose. And when you search for your next flight to St. Louis, you know you won’t be surprised at checkout. Low fares, no hidden fees. That’s our Transfarency® promise. And, as always, bags fly free. Enroll in our Click 'N Save® emails and stay up to date on our latest flight deals. Looking for tours, activities, and more hidden gems to add to your St. Louis adventure? Explore Southwest Airlines® Experiences and earn Rapid Rewards® points when you fly.
1First and second checked bags. Weight and size limits apply.
2Fare difference may apply.
How many Southwest flights from Ontario/LA to St. Louis occur daily?
There are 9 flights daily from Ontario/LA to St. Louis on Southwest Airlines.
What day is it cheapest to fly from Ontario/LA to St. Louis?
To find the cheapest day and time to fly Ontario/LA to St. Louis with Southwest, check out our Low Fare Calendar.
Can I rent a car at Lambert-St. Louis International Airport?
You can rent a car at Lambert-St. Louis International Airport—book yours with your flight.
Can I change my flight reservation for my flight from Ontario/LA to St. Louis?
Yes! Flights from Ontario/LA to St. Louis—or from here or there to anywhere—can be changed with no change fees. Fare difference may apply.
Where can I find the status of my flight from Ontario/LA to St. Louis?
Check the status of your upcoming Southwest flight here.
Where can I find answers to other questions about flying from Ontario/LA to St. Louis with Southwest?
Check out the Southwest Airlines® FAQs for answers about everything Southwest.
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