Southwest® flights from St. Louis to Ontario/LA from $174

Promo Code

Low fares from St. Louis to Ontario/LA

$

St. Louis (STL)to

Ontario/LA (ONT)
Depart: 11/14/2026

One-way

Basic

From
$174
Seen: 11 hrs ago

St. Louis (STL)to

Ontario/LA (ONT)
Depart: 11/16/2026

One-way

Basic

From
$179
Seen: 14 hrs ago

St. Louis (STL)to

Ontario/LA (ONT)
Depart: 10/22/2026

One-way

Basic

From
$179
Seen: 6 hrs ago

St. Louis (STL)to

Ontario/LA (ONT)
Depart: 10/24/2026

One-way

Basic

From
$179
Seen: 2 hrs ago

St. Louis (STL)to

Ontario/LA (ONT)
Depart: 12/17/2026

One-way

Basic

From
$179
Seen: 2 hrs ago

St. Louis (STL)to

Ontario/LA (ONT)
Depart: 11/12/2026

One-way

Basic

From
$179
Seen: 9 hrs ago

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Explore flights from St. Louis to Ontario/LA

Sep 2026
From$284*
Seen: 18 hrs ago
One Way/Basic
Oct 2026
From$179*
Seen: 6 hrs ago
One Way/Basic
Nov 2026
From$174*
Seen: 11 hrs ago
One Way/Basic
cmp-daily-histogram-bars-legend-min-price-aria-label $206
cmp-daily-histogram-bars-legend-max-price-aria-label $382
Displaying fares for September-2026
  • STL–ONT, 09/11/2026: From $372
    11

    Fri

    SEP

  • STL–ONT, 09/12/2026: From $284
    12

    Sat

  • STL–ONT: cmp-view-offers-disclaimer. Find Offers
    13

    Sun

  • STL–ONT: cmp-view-offers-disclaimer. Find Offers
    14

    Mon

  • STL–ONT: cmp-view-offers-disclaimer. Find Offers
    15

    Tue

  • STL–ONT: cmp-view-offers-disclaimer. Find Offers
    16

    Wed

  • STL–ONT, 09/17/2026: From $377
    17

    Thu

  • STL–ONT: cmp-view-offers-disclaimer. Find Offers
    18

    Fri

  • STL–ONT, 09/19/2026: From $284
    19

    Sat

  • STL–ONT, 09/20/2026: From $382
    20

    Sun

  • STL–ONT, 09/21/2026: From $367
    21

    Mon

  • STL–ONT: cmp-view-offers-disclaimer. Find Offers
    22

    Tue

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    23

    Wed

  • STL–ONT, 09/24/2026: From $304
    24

    Thu

  • STL–ONT, 09/25/2026: From $304
    25

    Fri

  • STL–ONT, 09/26/2026: From $284
    26

    Sat

  • STL–ONT, 09/27/2026: From $304
    27

    Sun

  • STL–ONT, 09/28/2026: From $304
    28

    Mon

  • STL–ONT: cmp-view-offers-disclaimer. Find Offers
    29

    Tue

  • STL–ONT, 09/30/2026: From $284
    30

    Wed

  • STL–ONT, 10/01/2026: From $231
    01

    Thu

    OCT

  • STL–ONT, 10/02/2026: From $217
    02

    Fri

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    03

    Sat

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    04

    Sun

  • STL–ONT, 10/05/2026: From $206
    05

    Mon

  • STL–ONT, 10/06/2026: From $206
    06

    Tue

  • STL–ONT, 10/07/2026: From $206
    07

    Wed

  • STL–ONT, 10/08/2026: From $256
    08

    Thu

  • STL–ONT, 10/09/2026: From $240
    09

    Fri

  • STL–ONT: cmp-view-offers-disclaimer. Find Offers
    10

    Sat

    • Range$206-$382

    *Fares displayed have been collected within the last 24 hours and may no longer be available at time of booking. Additional fees and charges for optional products and services may apply. Modifying this information may result in a different fare. To find the most updated fare, please visit Southwest.com. Fares listed are Basic, which are subject to additional terms and conditions.

    Flight Details

    Departing from:
    Lambert-St Louis Int'l Airport
    Arriving at:
    LA/Ontario International Airport
    Distance:
    1546 miles

    Route Information

    155† Weekly flights

    † Weekly flights based on DOT published scheduled average flights Monday through Sunday between 9/1/2025 and 9/30/2025. Note: route may not operate every day of the week.

    ‡ Nonstop flights based on DOT published scheduled average flights Monday through Sunday between 9/1/2025 and 9/30/2025.

    Questions we hear the most

    There are 155 weekly flights from St. Louis to Ontario/LA on Southwest Airlines.
    To find the lowest fares by day and time to fly St. Louis to Ontario/LA with Southwest, check out our Low Fare Calendar.
    You can rent a car at LA/Ontario International Airport book yours with your flight.
    Yes! Flights from St. Louis to Ontario/LA—or from here or there to anywhere—can be changed with no change fees. Fare difference may apply.
    Check the status of your upcoming Southwest flight.
    Check out the Southwest Airlines® Help Center for answers about everything Southwest.

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