Southwest® flights from Ontario/LA to St. Louis from $179

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Low fares from Ontario/LA to St. Louis

$

Ontario/LA (ONT)to

St. Louis (STL)
Depart: 11/05/2026

One-way

Basic

From
$179
Seen: 22 hrs ago

Ontario/LA (ONT)to

St. Louis (STL)
Depart: 11/04/2026

One-way

Basic

From
$179
Seen: 3 hrs ago

Ontario/LA (ONT)to

St. Louis (STL)
Depart: 11/02/2026

One-way

Basic

From
$179
Seen: 11 hrs ago

Ontario/LA (ONT)to

St. Louis (STL)
Depart: 12/07/2026

One-way

Basic

From
$179
Seen: 11 hrs ago

Ontario/LA (ONT)to

St. Louis (STL)
Depart: 10/31/2026

One-way

Basic

From
$179
Seen: 33 minutes ago

Ontario/LA (ONT)to

St. Louis (STL)
Depart: 11/23/2026

One-way

Basic

From
$206
Seen: 23 hrs ago

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Explore flights from Ontario/LA to St. Louis

Sep 2026
From$284*
Seen: 18 hrs ago
One Way/Basic
Oct 2026
From$179*
Seen: 34 minutes ago
One Way/Basic
Nov 2026
From$179*
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 $372
Displaying fares for September-2026
  • ONT–STL, 09/11/2026: From $372
    11

    Fri

    SEP

  • ONT–STL, 09/12/2026: From $310
    12

    Sat

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

    Sun

  • ONT–STL, 09/14/2026: From $372
    14

    Mon

  • ONT–STL, 09/15/2026: From $284
    15

    Tue

  • ONT–STL, 09/16/2026: From $284
    16

    Wed

  • ONT–STL: cmp-view-offers-disclaimer. Find Offers
    17

    Thu

  • ONT–STL, 09/18/2026: From $372
    18

    Fri

  • ONT–STL: cmp-view-offers-disclaimer. Find Offers
    19

    Sat

  • ONT–STL, 09/20/2026: From $372
    20

    Sun

  • ONT–STL, 09/21/2026: From $372
    21

    Mon

  • ONT–STL, 09/22/2026: From $284
    22

    Tue

  • ONT–STL, 09/23/2026: From $284
    23

    Wed

  • ONT–STL: cmp-view-offers-disclaimer. Find Offers
    24

    Thu

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

    Fri

  • ONT–STL: cmp-view-offers-disclaimer. Find Offers
    26

    Sat

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

    Sun

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

    Mon

  • ONT–STL, 09/29/2026: From $284
    29

    Tue

  • ONT–STL: cmp-view-offers-disclaimer. Find Offers
    30

    Wed

  • ONT–STL: cmp-view-offers-disclaimer. Find Offers
    01

    Thu

    OCT

  • ONT–STL: cmp-view-offers-disclaimer. Find Offers
    02

    Fri

  • ONT–STL: cmp-view-offers-disclaimer. Find Offers
    03

    Sat

  • ONT–STL: cmp-view-offers-disclaimer. Find Offers
    04

    Sun

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

    Mon

  • ONT–STL: cmp-view-offers-disclaimer. Find Offers
    06

    Tue

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

    Wed

  • ONT–STL, 10/08/2026: From $217
    08

    Thu

  • ONT–STL, 10/09/2026: From $217
    09

    Fri

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

    Sat

    • Range$206-$372

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

    Route Information

    152† 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 152 weekly flights from Ontario/LA to St. Louis on Southwest Airlines.
    To find the lowest fares by day and time to fly Ontario/LA to St. Louis with Southwest, check out our Low Fare Calendar.
    You can rent a car at Lambert-St Louis Int'l Airport book yours with your flight.
    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.
    Check the status of your upcoming Southwest flight.
    Check out the Southwest Airlines® Help Center for answers about everything Southwest.

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