Southwest® flights from Ontario/LA to Seattle/Tacoma from $129

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Low fares from Ontario/LA to Seattle/Tacoma

$

Ontario/LA (ONT)to

Seattle/Tacoma (SEA)
Depart: 09/26/2026

One-way

Basic

From
$129
Seen: 1 hour ago

Ontario/LA (ONT)to

Seattle/Tacoma (SEA)
Depart: 11/03/2026

One-way

Basic

From
$134
Seen: 14 hrs ago

Ontario/LA (ONT)to

Seattle/Tacoma (SEA)
Depart: 10/14/2026

One-way

Basic

From
$134
Seen: 17 hrs ago

Ontario/LA (ONT)to

Seattle/Tacoma (SEA)
Depart: 09/23/2026

One-way

Basic

From
$134
Seen: 17 hrs ago

Ontario/LA (ONT)to

Seattle/Tacoma (SEA)
Depart: 10/03/2026

One-way

Basic

From
$134
Seen: 4 hrs ago

Ontario/LA (ONT)to

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

One-way

Basic

From
$134
Seen: 1 hour ago

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Explore flights from Ontario/LA to Seattle/Tacoma

Aug 2026
From$257*
Seen: 6 hrs ago
One Way/Basic
Sep 2026
From$129*
Seen: 1 hour ago
One Way/Basic
Oct 2026
From$134*
Seen: 16 hrs ago
One Way/Basic
cmp-daily-histogram-bars-legend-min-price-aria-label $134
cmp-daily-histogram-bars-legend-max-price-aria-label $303
Displaying fares for August-2026
  • ONT–SEA, 08/22/2026: From $257
    22

    Sat

    AUG

  • ONT–SEA, 08/23/2026: From $303
    23

    Sun

  • ONT–SEA, 08/24/2026: From $303
    24

    Mon

  • ONT–SEA, 08/25/2026: From $262
    25

    Tue

  • ONT–SEA, 08/26/2026: From $262
    26

    Wed

  • ONT–SEA, 08/27/2026: From $303
    27

    Thu

  • ONT–SEA, 08/28/2026: From $303
    28

    Fri

  • ONT–SEA, 08/29/2026: From $257
    29

    Sat

  • ONT–SEA, 08/30/2026: From $303
    30

    Sun

  • ONT–SEA: cmp-view-offers-disclaimer. Find Offers
    31

    Mon

  • ONT–SEA, 09/01/2026: From $262
    01

    Tue

    SEP

  • ONT–SEA, 09/02/2026: From $262
    02

    Wed

  • ONT–SEA, 09/03/2026: From $244
    03

    Thu

  • ONT–SEA, 09/04/2026: From $244
    04

    Fri

  • ONT–SEA, 09/05/2026: From $239
    05

    Sat

  • ONT–SEA, 09/06/2026: From $244
    06

    Sun

  • ONT–SEA, 09/07/2026: From $244
    07

    Mon

  • ONT–SEA, 09/08/2026: From $244
    08

    Tue

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

    Wed

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

    Thu

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

    Fri

  • ONT–SEA: cmp-view-offers-disclaimer. Find Offers
    12

    Sat

  • ONT–SEA, 09/13/2026: From $189
    13

    Sun

  • ONT–SEA, 09/14/2026: From $189
    14

    Mon

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

    Tue

  • ONT–SEA, 09/16/2026: From $174
    16

    Wed

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    17

    Thu

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

    Fri

  • ONT–SEA, 09/19/2026: From $134
    19

    Sat

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    20

    Sun

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

    Mon

    • Range$134-$303

    *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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