$160 Cheap Delta flights St. Louis (STL) to Ontario (ONT)

View $160 flight on Tue, Sep 30, 2025Opens in a new window

$160 Cheap Delta flights St. Louis (STL) to Ontario (ONT)

Prices were available within the past 7 days and start at $160 for one-way flights and for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

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Flights from St. Louis (STL) to Ontario (ONT)
Origin airport
Lambert-St. Louis Intl.
Destination airport
Los Angeles - Ontario Intl.
Airlines serving
Alaska Airlines, American Airlines, Delta, Frontier Airlines, Hawaiian Airlines, Southwest Airlines, United
Popular airline
Delta
Distance
1541 mi

Frequently asked questions

How much is a Delta Air Lines flight from Lambert-St. Louis Intl. Airport (STL) to Los Angeles - Ontario Intl. Airport (ONT)?
Landing cheap one-way Delta Air Lines flights from STL to ONT from $160 on Expedia is easy --- just filter by "Price (lowest to highest)." Alternatively, check out our affordable round-trip fares for your next adventure.**These prices were available on Expedia within the past 7 days, for flights departing within the next year. Prices and availability are subject to change. Additional terms apply.
What is the cheapest month to fly from STL to ONT with Delta Air Lines?
Browse for one-way or round-trip flights to Ontario in January or April. You could find an affordable fare with Delta Air Lines during these quieter months.
What is the cheapest time to book flights from Lambert-St. Louis Intl. Airport (STL) to Los Angeles - Ontario Intl. Airport (ONT) with Delta Air Lines?
Search for cheap Delta Air Lines flights from Lambert-St. Louis Intl. Airport (STL) to Los Angeles - Ontario Intl. Airport (ONT) one to three months before your departure. Travelers who book domestic flights 34 to 86 days in advance can save 25% compared to those who book just 6 to 12 days ahead. Regardless of fare class and itinerary, the best day to book a domestic flight is usually Sunday and the most expensive is typically Monday. Passengers who book on a Sunday can save 6% on average compared to those who book their travel on a Monday.**Ideal booking window recommendation is based on average round-trip ticket prices for January through November for 2024. Best day of the week to book recommendation is based on average round-trip ticket prices for January through October 2024. All data sourced from ARC's global airline sales database.
Does Delta Air Lines fly nonstop from Lambert-St. Louis Intl. Airport (STL) to Los Angeles - Ontario Intl. Airport (ONT)?
To figure out if there's a direct journey from STL to ONT with Delta Air Lines or other carriers, check the "Nonstop" box when looking for flights.
What is the earliest Delta Air Lines flight from STL to ONT?
Filter your results by "Morning" and "Early Morning" to find the earliest flights from STL to ONT. Heading off early means you're less likely to experience cancellations.**Most reliable time of the day recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.
What airports does Delta Air Lines fly into in Ontario?
Delta Air Lines flights from Lambert-St. Louis Intl. Airport (STL) to Ontario land at Los Angeles - Ontario Intl. Airport (ONT). This is the main entry point to this city.
Why fly with Delta Air Lines from STL to ONT?
Delta Air Lines makes traveling from STL to ONT enjoyable with an excellent in-flight experience and a rewarding loyalty program. You also have the chance to earn points with Delta SkyMiles. Be sure to sign up to our free One Key™ rewards program to earn OneKeyCash™*, which can be redeemed on future bookings.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.
Can I change or cancel my Delta Air Lines flight from Lambert-St. Louis Intl. Airport (STL) to Los Angeles - Ontario Intl. Airport (ONT)?
Changes are typically free within 24 hours of booking, but your airline may charge a fee after that. For more details about altering your reservation, head to your "Trips," select your flight and click on "Manage Booking." If you'd like the flexibility to change your plans without additional costs, check the "No cancel fee" or "Changes included" filter when planning your next adventure.

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*Available to One Key members.