Southwest® flights from Ontario/LA to Seattle/Tacoma from $124

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Low fares from Ontario/LA to Seattle/Tacoma

$

Ontario/LA (ONT)to

Seattle/Tacoma (SEA)
Depart: 08/25/2026

One-way

Basic

From
$124
Seen: 14 hrs ago

Ontario/LA (ONT)to

Seattle/Tacoma (SEA)
Depart: 08/27/2026

One-way

Basic

From
$124
Seen: 4 hrs ago

Ontario/LA (ONT)to

Seattle/Tacoma (SEA)
Depart: 08/24/2026

One-way

Basic

From
$124
Seen: 7 hrs ago

Ontario/LA (ONT)to

Seattle/Tacoma (SEA)
Depart: 08/26/2026

One-way

Basic

From
$124
Seen: 18 hrs ago

Ontario/LA (ONT)to

Seattle/Tacoma (SEA)
Depart: 08/28/2026

One-way

Basic

From
$124
Seen: 4 hrs ago

Ontario/LA (ONT)to

Seattle/Tacoma (SEA)
Depart: 09/30/2026

One-way

Basic

From
$129
Seen: 16 hrs ago

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Explore flights from Ontario/LA to Seattle/Tacoma

Aug 2026
From$124*
Seen: 4 hrs ago
One Way/Basic
Sep 2026
From$129*
Seen: 7 hrs ago
One Way/Basic
Oct 2026
From$129*
Seen: 1 minute ago
One Way/Basic
cmp-daily-histogram-bars-legend-min-price-aria-label $124
cmp-daily-histogram-bars-legend-max-price-aria-label $414
Displaying fares for August-2026
  • ONT–SEA: cmp-view-offers-disclaimer. Find Offers
    02

    Sun

    AUG

  • ONT–SEA, 08/03/2026: From $409
    03

    Mon

  • ONT–SEA, 08/04/2026: From $414
    04

    Tue

  • ONT–SEA, 08/05/2026: From $414
    05

    Wed

  • ONT–SEA, 08/06/2026: From $414
    06

    Thu

  • ONT–SEA, 08/07/2026: From $324
    07

    Fri

  • ONT–SEA, 08/08/2026: From $319
    08

    Sat

  • ONT–SEA: cmp-view-offers-disclaimer. Find Offers
    09

    Sun

  • ONT–SEA, 08/10/2026: From $324
    10

    Mon

  • ONT–SEA, 08/11/2026: From $324
    11

    Tue

  • ONT–SEA, 08/12/2026: From $324
    12

    Wed

  • ONT–SEA, 08/13/2026: From $324
    13

    Thu

  • ONT–SEA, 08/14/2026: From $194
    14

    Fri

  • ONT–SEA, 08/15/2026: From $194
    15

    Sat

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

    Sun

  • ONT–SEA, 08/17/2026: From $194
    17

    Mon

  • ONT–SEA, 08/18/2026: From $194
    18

    Tue

  • ONT–SEA, 08/19/2026: From $194
    19

    Wed

  • ONT–SEA, 08/20/2026: From $194
    20

    Thu

  • ONT–SEA: cmp-view-offers-disclaimer. Find Offers
    21

    Fri

  • ONT–SEA, 08/22/2026: From $154
    22

    Sat

  • ONT–SEA, 08/23/2026: From $154
    23

    Sun

  • ONT–SEA, 08/24/2026: From $124
    24

    Mon

  • ONT–SEA, 08/25/2026: From $124
    25

    Tue

  • ONT–SEA, 08/26/2026: From $124
    26

    Wed

  • ONT–SEA, 08/27/2026: From $124
    27

    Thu

  • ONT–SEA, 08/28/2026: From $124
    28

    Fri

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

    Sat

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

    Sun

  • ONT–SEA, 08/31/2026: From $139
    31

    Mon

  • ONT–SEA, 09/01/2026: From $129
    01

    Tue

    SEP

    • Range$124-$414

    *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:
    Seattle/Tacoma International Airport
    Distance:
    956 miles

    Route Information

    148† 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 148 weekly flights from Ontario/LA to Seattle/Tacoma on Southwest Airlines.
    To find the lowest fares by day and time to fly Ontario/LA to Seattle/Tacoma with Southwest, check out our Low Fare Calendar.
    You can rent a car at Seattle/Tacoma International Airport book yours with your flight.
    Yes! Flights from Ontario/LA to Seattle/Tacoma—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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