Flights from Ontario/LA, CA to St. Louis, MO

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Best Deals on Flights From Ontario/LA, CA (ONT) to St. Louis, MO (STL)

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Sep 2026
No results for this month.
Oct 2026
from$90*
Last seen: 8 hours ago
One-way/Economy
Nov 2026
from$81*
Last seen: 10 hours ago
One-way/Economy
cmp-daily-histogram-bars-legend-min-price-aria-label $90
cmp-daily-histogram-bars-legend-max-price-aria-label $257
Displaying fares for September-2026
  • ONT–STL: cmp-view-offers-disclaimer. Find Offers
    29

    Tue

    SEP

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    30

    Wed

  • ONT–STL, Oct 1, 2026: from $257
    01

    Thu

    OCT

  • ONT–STL, Oct 2, 2026: from $251
    02

    Fri

  • ONT–STL, Oct 3, 2026: from $193
    03

    Sat

  • ONT–STL, Oct 4, 2026: from $257
    04

    Sun

  • ONT–STL, Oct 5, 2026: from $251
    05

    Mon

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    06

    Tue

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    07

    Wed

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    08

    Thu

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    09

    Fri

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    10

    Sat

  • ONT–STL: cmp-view-offers-disclaimer. Find Offers
    11

    Sun

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    12

    Mon

  • ONT–STL, Oct 13, 2026: from $199
    13

    Tue

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

    Wed

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    15

    Thu

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    16

    Fri

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    17

    Sat

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    18

    Sun

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    19

    Mon

  • ONT–STL, Oct 20, 2026: from $109
    20

    Tue

  • ONT–STL, Oct 21, 2026: from $90
    21

    Wed

  • ONT–STL, Oct 22, 2026: from $124
    22

    Thu

  • ONT–STL, Oct 23, 2026: from $196
    23

    Fri

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

    Sat

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    25

    Sun

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    26

    Mon

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    27

    Tue

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    28

    Wed

    • Range$90-$257

    *Prices found by others in the previous 48 hours for round-trip flights. Prices shown may also require membership in our travel club, Discount Den.

    Flights Deals from Ontario/LA, CA to St. Louis, MO on Frontier

    $
    Flights Deals from Ontario/LA, CA to St. Louis, MO on Frontier
    From
    To
    Ontario/LA, CA (ONT)St. Louis, MO (STL)One-way
    /
    Discount Den Basic Fare    		Departing Jan 17, 2027

    From

    $343

    Last seen: 10 hours ago

    *Prices found by others in the previous 48 hours for one-way flights. Prices shown may also require membership in our travel club, Discount Den®.

    Ontario/LA, CA St. Louis, MO

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