Southwest® flights from Ontario/LA to Seattle/Tacoma from $84

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Low fares from Ontario/LA to Seattle/Tacoma

$

Ontario/LA (ONT)to

Seattle/Tacoma (SEA)
Depart: 12/11/2026

One-way

Basic

From
$84
Seen: 15 hrs ago

Ontario/LA (ONT)to

Seattle/Tacoma (SEA)
Depart: 11/06/2026

One-way

Basic

From
$84
Seen: 2 hrs ago

Ontario/LA (ONT)to

Seattle/Tacoma (SEA)
Depart: 10/08/2026

One-way

Basic

From
$89
Seen: 19 hrs ago

Ontario/LA (ONT)to

Seattle/Tacoma (SEA)
Depart: 10/09/2026

One-way

Basic

From
$89
Seen: 12 hrs ago

Ontario/LA (ONT)to

Seattle/Tacoma (SEA)
Depart: 11/10/2026

One-way

Basic

From
$89
Seen: 12 hrs ago

Ontario/LA (ONT)to

Seattle/Tacoma (SEA)
Depart: 10/16/2026

One-way

Basic

From
$89
Seen: 20 hrs ago

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Explore flights from Ontario/LA to Seattle/Tacoma

Sep 2026
From$189*
Seen: 6 hrs ago
One Way/Basic
Oct 2026
From$89*
Seen: 15 hrs ago
One Way/Basic
Nov 2026
From$84*
Seen: 2 hrs ago
One Way/Basic
cmp-daily-histogram-bars-legend-min-price-aria-label $89
cmp-daily-histogram-bars-legend-max-price-aria-label $313
Displaying fares for September-2026
  • ONT–SEA: cmp-view-offers-disclaimer. Find Offers
    10

    Thu

    SEP

  • ONT–SEA, 09/11/2026: From $313
    11

    Fri

  • ONT–SEA, 09/12/2026: From $267
    12

    Sat

  • ONT–SEA, 09/13/2026: From $313
    13

    Sun

  • ONT–SEA, 09/14/2026: From $313
    14

    Mon

  • ONT–SEA, 09/15/2026: From $272
    15

    Tue

  • ONT–SEA, 09/16/2026: From $272
    16

    Wed

  • ONT–SEA, 09/17/2026: From $313
    17

    Thu

  • ONT–SEA, 09/18/2026: From $313
    18

    Fri

  • ONT–SEA, 09/19/2026: From $267
    19

    Sat

  • ONT–SEA, 09/20/2026: From $313
    20

    Sun

  • ONT–SEA, 09/21/2026: From $313
    21

    Mon

  • ONT–SEA, 09/22/2026: From $272
    22

    Tue

  • ONT–SEA, 09/23/2026: From $244
    23

    Wed

  • ONT–SEA, 09/24/2026: From $244
    24

    Thu

  • ONT–SEA: cmp-view-offers-disclaimer. Find Offers
    25

    Fri

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

    Sat

  • ONT–SEA: cmp-view-offers-disclaimer. Find Offers
    27

    Sun

  • ONT–SEA, 09/28/2026: From $244
    28

    Mon

  • ONT–SEA, 09/29/2026: From $244
    29

    Tue

  • ONT–SEA, 09/30/2026: From $189
    30

    Wed

  • ONT–SEA, 10/01/2026: From $89
    01

    Thu

    OCT

  • ONT–SEA, 10/02/2026: From $189
    02

    Fri

  • ONT–SEA, 10/03/2026: From $189
    03

    Sat

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

    Sun

  • ONT–SEA, 10/05/2026: From $89
    05

    Mon

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

    Tue

  • ONT–SEA, 10/07/2026: From $89
    07

    Wed

  • ONT–SEA, 10/08/2026: From $89
    08

    Thu

  • ONT–SEA, 10/09/2026: From $89
    09

    Fri

    • Range$89-$313

    *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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