HomeSearch by dateVacation packagesHotelsFlight dealsCar rentalTravel tips & news
Ontario

$57+ Cheap flights from Seattle to Ontario (SEA - ONT)

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 7/15. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — ONT
Apr 29 — May 61
Tue 4/29
Tue 5/6
1 adult, Economy
We work with more than 300 partners to bring you better travel deals

Find cheap flights from Seattle to Ontario with Cheapflights

1. Tell us where you want to go

Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”

2. Select your favorite providers

We find the providers serving your travel needs. Choose up to four travel providers to compare side-by-side for flights, hotels, or car rentals.

3. Compare prices and book

Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.

Cheapflights Tip: The best prices from Seattle/Tacoma Intl to Ontario are usually found in September or August, booked 72 days in advance, depart on a Thursday or Tuesday and return on a Friday

Cheap flight deals from Seattle to Ontario

Discover tips and strategies to find the most affordable flight options for your journey from Seattle (SEA) to Ontario (ONT). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated April 24, 2025.

Most accurate provider

FlightHub
3 stars

Most trusted provider

eDreams
3 stars

Round-trip from

$100
(Kiwi.com)

One-way from

$57
(Cheapflightsfares)

Popular in

December

Cheapest in

September

Average price

$228

Good round-trip deal

$174 or less

Good one-way deal

$98 or less
Provider with most accurate pricing for Seattle/Tacoma Intl-Ontario flight deals.
Search Deals
Provider most trusted by Cheapflights users for Seattle/Tacoma Intl-Ontario flights.
Search Deals
From Seattle/Tacoma Intl to Ontario
Search Deals
One-way flight from Seattle/Tacoma Intl to Ontario
Search Deals
Highest demand for flights based on searches. 12% potential increase in price ($27 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 3% potential price decrease ($7 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in April 2025
Search Deals
Price to beat on a round-trip flight from Seattle/Tacoma Intl to Ontario.
Search Deals
Price to beat on a one-way flight from Seattle/Tacoma Intl to Ontario.
Search Deals

Find flight deals from Seattle to Ontario

Cheapest flights from Seattle to Ontario
Explore the most affordable flight options available from Seattle to Ontario. Find the lowest fares from popular airlines and budget airlines, with prices last updated on April 24, 2025.

This Kiwi.com deal was found by Cheapflights users on 4/23. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 6/111:50 pmSEA - ONT
Nonstop2h 40mFrontier
Tue 6/1710:03 amONT - SEA
Nonstop2h 46mFrontier
Deal found 4/23$100
This Orbitz deal was found by Cheapflights users on 4/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Orbitz is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/203:53 pmSEA - ONT
Nonstop2h 32mMultiple Airlines
Tue 5/2711:35 amONT - SEA
Nonstop3h 01mMultiple Airlines
Deal found 4/22$128
This Alaska Airlines deal was found by Cheapflights users on 4/23. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/145:55 pmSEA - ONT
Nonstop2h 34mAlaska Airlines
Tue 5/206:00 amONT - SEA
Nonstop2h 42mAlaska Airlines
Deal found 4/23$157
This Delta deal was found by Cheapflights users on 4/23. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/173:35 pmSEA - ONT
Nonstop2h 45mDelta
Tue 5/202:55 pmONT - SEA
Nonstop3h 00mDelta
Deal found 4/23$167
This United Airlines deal was found by Cheapflights users on 4/23. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/2411:40 amSEA - ONT
1 stop5h 59mUnited Airlines
Wed 5/281:36 pmONT - SEA
1 stop4h 49mUnited Airlines
Deal found 4/23$205
This Southwest deal was found by Cheapflights users on 4/23. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/156:00 amSEA - ONT
1 stop5h 00mSouthwest
Mon 5/194:55 pmONT - SEA
1 stop7h 35mSouthwest
Deal found 4/23$227

Cheapflights Fare Finder

Customize your flight search to find flights from Seattle to Ontario that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated April 24, 2025.
Use the filters below to find and compare flights from Seattle to Ontario that are best for you.

Fly from

Seattle

Fly to

Ontario

Route

Depart

Return

Price

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Wed 6/11

1:50 pm-4:30 pm

Nonstop2h 40m

Ontario

Tue 6/17

10:03 am-12:49 pm

Nonstop2h 46m

$100

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Tue 5/20

3:53 pm-6:25 pm

Nonstop2h 32m

Ontario

Tue 5/27

11:35 am-2:36 pm

Nonstop3h 01m

$128

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Wed 5/14

5:55 pm-8:29 pm

Nonstop2h 34m

Ontario

Tue 5/20

6:00 am-8:42 am

Nonstop2h 42m

$157

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sat 5/17

3:35 pm-6:20 pm

Nonstop2h 45m

Ontario

Tue 5/20

2:55 pm-5:55 pm

Nonstop3h 00m

$167

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sat 5/24

11:40 am-5:39 pm

1 stop5h 59m

Ontario

Wed 5/28

1:36 pm-6:25 pm

1 stop4h 49m

$205

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Thu 5/15

6:00 am-11:00 am

1 stop5h 00m

Ontario

Mon 5/19

4:55 pm-12:30 am

1 stop7h 35m

$227

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Thu 5/15

3:53 pm-6:25 pm

Nonstop2h 32m

Ontario

Sun 5/18

6:00 am-8:42 am

Nonstop2h 42m

$252

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Tue 7/15

1:42 pm-4:36 pm

Nonstop2h 54m

$57

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Wed 5/14

5:55 pm-8:29 pm

Nonstop2h 34m

$79

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sat 5/24

10:00 am-5:06 pm

1 stop7h 06m

$118

Flights are sorted by cheapest round-trip flights first.

Deals found on 4/23

Showing 1-10 of 14 results
1
2

Compare providers for flights from Seattle to Ontario

Provider information is updated monthly. Please note that these providers often have deals for this flight, but the availability may vary on a day-by-day basis on Cheapflights.
Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from Seattle to Ontario in April.
ProviderPrice AccuracyTrust Score*
ExpediaPrice Accuracy1 starTrust Score*3 stars
FlightHubPrice Accuracy3 starsTrust Score*2 stars
eDreamsPrice Accuracy3 starsTrust Score*3 stars
CheapflightsfaresPrice Accuracy3 starsTrust Score*2 stars
Kiwi.comPrice Accuracy3 starsTrust Score*3 stars
PricelinePrice Accuracy1 starTrust Score*3 stars
CheapOairPrice Accuracy1 starTrust Score*3 stars
JustAirTicketPrice Accuracy-Trust Score*3 stars
CheapfaremartPrice Accuracy-Trust Score*1 star
GotogatePrice Accuracy3 starsTrust Score*2 stars

*The Trust Score is based on feedback from users after their booking experience. It measures overall satisfaction, helping us identify issues like hidden fees, problems during the ticketing process, and the quality of customer service. This score is our best indicator of the provider's quality and reliability.

  • Most accurate provider: When it comes to deals on Seattle-Ontario flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on Seattle-Ontario flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from Seattle-Ontario flight searches over the past month and is updated monthly.
  • Most trusted provider: When it comes to deals on Seattle-Ontario flights, Cheapflights users trust eDreams the most. eDreams has received a user feedback score of 3 out of 3 stars (3 being the best), meaning they have been trusted the most by Cheapflights users looking for Seattle-Ontario flight deals. Provider user feedback score is based on Cheapflights searches over the past month and is updated monthly.

The best insider tips for Seattle to Ontario flights

Snippets provided in this section are AI-generated based on a summarization of Cheapflights-commissioned articles. The articles are presented as-is, for general informational purposes only, and may not be up-to-date. The opinions contained in the articles are original to the author and reflect their authentic experience, which may vary significantly from the experience of others.
Cheapflights partnered with top experts to bring you the best recommendations for your Seattle to Ontario trip
Airlines
Frontier

Frontier's UpFront Plus seats offer a guaranteed empty middle seat for added comfort.


Frontier's Zone 1 boarding is available with carry-on purchase or special fare bundles.

Read more about Frontierby Marisa Garcia
Alaska Airlines

Alaska's Premium Class offers extra legroom and free cocktails, enhancing comfort on short flights.


Alaska Airlines' Wi-Fi is a flat fee, ideal for business travelers needing connectivity during flights.

Read more about Alaska Airlinesby Robert Schrader
Airports
SEA

Plan to arrive at SEA two hours before your flight. Use SEA Spot Saver for free security appointments to reduce wait times.

Read more about SEAby Brandon Schultz
ONT

Consider renting a car at ONT for convenient travel in the L.A. area. ONT's rental center offers quick access to I-10.

Read more about ONTby Bill Fink
Our travel experts
Marisa Garcia

Marisa Garcia

Expert on Frontier

Marisa Garcia

Marisa Garcia

Marisa knows planes inside and out, spending 16 years working on aircraft in hangars at airports around the world. She is an aviation industry expert, specialized in airline interiors and regulations. Ten years ago, she pivoted to journalism. She shares her insights in leading aviation, travel, and business publications and on her site FlightChic.

Read more
Robert Schrader

Robert Schrader

Expert on Alaska Airlines

Robert Schrader

Robert Schrader

One of the web's original travel bloggers, Robert launched his first site Leave Your Daily Hell in 2009. Since then, he's expanded into destination niche sites (one each for Japan, Thailand and Taiwan), in addition to having written for the inflight magazines of Singapore Airlines and Korean Air. Overall, he's visited nearly 100 countries, and flies business as often as possible.

Read more
Bill Fink

Bill Fink

Expert on ONT

Bill Fink

Bill Fink

Bill is an award-winning travel writer with extensive credits covering airlines and the aviation industry for publications including AARP, AFAR, The Points Guy and Yahoo. Based in Portland, Oregon, Bill has traveled to more than 75 countries - and been late for his flight in most of them. He once achieved top-level frequent flier status for all of American, Delta and United Airlines during a single year.

Read more
Brandon Schultz

Brandon Schultz

Expert on SEA

Brandon Schultz

Brandon Schultz

Brandon Schultz is an award-winning food and travel writer based in New York City. His work has appeared in Forbes, AAA, Thrillist, Travel + Leisure, and The Daily Meal, among many others, and he is the author of 6 books, including 3 cookbooks.

Read more

Best time to book a flight from Seattle to Ontario

Have a flexible travel schedule? Discover the best time to fly to Ontario from Seattle with our price prediction graph.
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

Everything you need to know about your flight from Seattle to Ontario

How far ahead should I book a flight from Seattle to Ontario?

Use this chart to determine the optimal time to book a round-trip flight from Seattle to Ontario. Price data was last updated on April 18, 2025.

The best time to book flights from Seattle to Ontario is 72 days before your desired departure date. The cost of your flight will likely increase significantly if you book two weeks in advance of your flight.

What is the cheapest month to book a flight from Seattle to Ontario?

Currently, August is the cheapest month in which you can book a flight from Seattle to Ontario (average of $246). Flying from Seattle to Ontario in March is currently the most expensive (average of $328). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

What is the cheapest time of day to fly from SEA to ONT?

Find hourly flight availability from Seattle to Ontario. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated April 24, 2025.

A simple way to save on the total cost of your ticket is to fly from Seattle to Ontario at noon. If you’re flexible enough to do this you can expect to save up to 32% on your trip compared to booking a flight in the morning.

What is the cheapest day to fly from Seattle to Ontario?

Use this chart to determine the cheapest time to fly round-trip from Seattle to Ontario. Price data was last updated on March 30, 2025.

Travelers seeking maximum savings on their Seattle to Ontario flight should consider departing on Tuesday at noon when fares are most often at their lowest. Monday afternoons flights should be avoided if possible as fares are typically the most expensive at this time.

Weekly flight availability from Seattle to Ontario

Explore weekly flight availability from Seattle to Ontario. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated April 24, 2025.

The most flights from SEA to ONT are scheduled on a Wednesday (17 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (7 on average).

Rainfall in Ontario by month

Plan your trip to Ontario by taking into account the average rainfall totals by month.

In terms of precipitation, rainfall in Ontario ranges from 0.1 - 3.4 inches per month. February is typically the wettest month, when rainfall can reach 3.4 in. June is typically the driest time to visit Ontario when rainfall is around 0.1 in.

Temperature in Ontario by month

Plan your trip to Ontario by taking into account the average temperature totals by month.

If weather is an important factor for your trip to Ontario, use this chart to help with planning. For those seeking warmer temperatures, August is the ideal time of year to visit, when temperatures reach an average of 78.8 F. Travelers looking to avoid the cold should look outside of December, when temperatures are typically at their lowest (around 53.6 F).

Reviews of airlines servicing Ontario

Get insights into the airlines that provide service to Ontario. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Ontario. Reviews last updated April 24, 2025.
Read through reviews of airlines operating flights from Seattle to Ontario, such as Alaska Airlines, Southwest and Delta. You can also see how each airline compares in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
8.0
Very good
9,918 reviews

Food

7.1

Crew

8.5

Comfort

7.9

Boarding

8.2

Entertainment

7.1

Overall

8.0

Reviews

1 / 20
8.0
Excellent

Anonymous,Aug 2024

SEA - LAS

Seats were not that comfy especially for someone with big hips 😥
Alaska Airlines
8.0
Very good
9,918 reviews
Alaska Airlines
8.0
Very good
9,918 reviews

Food

7.1

Crew

8.5

Comfort

7.9

Boarding

8.2

Entertainment

7.1

Overall

8.0

Reviews

1 / 20
8.0
Excellent

Anonymous,Aug 2024

SEA - LAS

Seats were not that comfy especially for someone with big hips 😥
Southwest
8.0
Very good
4,287 reviews
Alaska Airlines
8.0
Very good
9,918 reviews

Food

7.1

Crew

8.5

Comfort

7.9

Boarding

8.2

Entertainment

7.1

Overall

8.0

Reviews

1 / 20
8.0
Excellent

Anonymous,Aug 2024

SEA - LAS

Seats were not that comfy especially for someone with big hips 😥
Delta
8.0
Very good
7,920 reviews
Alaska Airlines
8.0
Very good
9,918 reviews

Food

7.1

Crew

8.5

Comfort

7.9

Boarding

8.2

Entertainment

7.1

Overall

8.0

Reviews

1 / 20
8.0
Excellent

Anonymous,Aug 2024

SEA - LAS

Seats were not that comfy especially for someone with big hips 😥
Hawaiian Airlines
7.9
Good
2,393 reviews
Alaska Airlines
8.0
Very good
9,918 reviews

Food

7.1

Crew

8.5

Comfort

7.9

Boarding

8.2

Entertainment

7.1

Overall

8.0

Reviews

1 / 20
8.0
Excellent

Anonymous,Aug 2024

SEA - LAS

Seats were not that comfy especially for someone with big hips 😥
United Airlines
7.4
Good
8,685 reviews
Alaska Airlines
8.0
Very good
9,918 reviews

Food

7.1

Crew

8.5

Comfort

7.9

Boarding

8.2

Entertainment

7.1

Overall

8.0

Reviews

1 / 20
8.0
Excellent

Anonymous,Aug 2024

SEA - LAS

Seats were not that comfy especially for someone with big hips 😥

Related info for your journey

Find useful and relevant information for your journey from Seattle to Ontario. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airports do I use to fly from Seattle to Ontario?

    Booking a flight from Seattle/Tacoma Intl (SEA) to Ontario (ONT) is your only option if you wish to fly from Seattle to Ontario. On a typical day, there are 12 flights from Seattle/Tacoma Intl to Ontario, all of which are around 2h 31m for a nonstop flight. You can also purchase a plane ticket from 6 airlines when you book a flight from Seattle/Tacoma Intl to Ontario.

  • How popular is this Seattle to Ontario flight route?

    This flight path from Seattle/Tacoma Intl to Ontario was viewed by 69 users in the past month. Keep an eye out for changes in search interest prior to high and low season.

  • What are the cheapest airlines flying from Seattle to Ontario round-trip?

    Our cheapest airline available from Seattle to Ontario is Frontier. Our recent data shows that you can find tickets from as low as $100 on this airline. Additional options worth looking into are Alaska Airlines and Delta, starting at $157 and $167 round-trip. Frontier is priced at 47% lower than the current average price of a flight leaving 3 months from now.

  • What are the cheapest airlines to fly from Seattle to Ontario one-way?

    For one-way options, check prices for Frontier. According to our data, you can fly for as low as $57. Users have also found prices from $79 and $118 on Hawaiian Airlines and Alaska Airlines, respectively.

  • What are the most reliable airlines from Seattle to Ontario?

    Before booking your flight to Ontario from Seattle, check out the most reliable airlines to get you to your destination on time: WestJet (98%), Korean Air (97%), KLM( 95%).

  • What are the cheapest flights from Seattle to Ontario?

    Looking at all options, your cheapest flight can be booked for $55. While the most popular route (Seattle/Tacoma Intl - Ontario) can be booked for $87 on average our data indicates $304 when flying from Seattle to Ontario.

  • Can I find deals for flights from Seattle to Ontario that include hotel bookings?

    Yes. In addition to deals on Seattle to Ontario flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Seattle to Ontario?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Seattle to Ontario.

  • Can I find deals for business class flights from Seattle to Ontario?

    Yes. Cheapflights offers flight deals from Seattle to Ontario by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from Seattle to Ontario?

    Currently, August is the cheapest month in which you can book a flight from Seattle to Ontario (average of $246). Flying from Seattle to Ontario in March is currently the most expensive (average of $328). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Alternative routes for Seattle to Ontario

See prices for flight routes from nearby airports that may be better suited for you.
Seattle to Los Angeles flights
Seattle to Las Vegas flights
Seattle to Santa Ana flights
Seattle to San Diego flights
Seattle to Burbank flights
Seattle to San Francisco flights
Portland to Los Angeles flights
Seattle to San Jose flights
Everett to Las Vegas flights
Seattle to Oakland flights
Portland to Las Vegas flights
Portland to San Diego flights
Seattle to Palm Springs flights
Seattle to Sacramento flights
Portland to Burbank flights
Everett to Los Angeles flights
Portland to San Francisco flights
Portland to Santa Ana flights
Portland to Ontario flights
Seattle to Reno flights
Portland to Palm Springs flights
Everett to San Francisco flights
Portland to San Jose flights
Everett to San Diego flights
Portland to Sacramento flights
Everett to Santa Ana flights
Portland to Oakland flights
Seattle to San Luis Obispo flights
Portland to Reno flights
Spokane to Las Vegas flights
Seattle to Fresno flights
Spokane to Los Angeles flights
Spokane to San Diego flights
Seattle to Santa Barbara flights
Seattle to Long Beach flights
Portland to Santa Barbara flights
Seattle to Monterey flights
Portland to San Luis Obispo flights
Pasco to Los Angeles flights
Pasco to San Francisco flights
Portland to Long Beach flights
Seattle to Medford flights
Seattle to Santa Rosa flights
Everett to San Jose flights
Spokane to San Francisco flights
Portland to Santa Rosa flights
Pasco to Las Vegas flights
Seattle to Bakersfield flights
Portland to Medford flights

Top 6 airlines flying from Seattle to Ontario

Discover the top 6 airlines that operate flights from Seattle to Ontario. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated April 24, 2025.
AirlineCheapestAverageFlexibilityOn-time
Spirit AirlinesCheapest$40Average$96FlexibilityNo cancel feeOn-time65%
FrontierCheapest$55Average$137FlexibilityNo cancel feeOn-time62%
Hawaiian AirlinesCheapest$95Average$228FlexibilityNo cancel feeOn-time85%
DeltaCheapest$117Average$259FlexibilityNo cancel feeOn-timeN/A
Alaska AirlinesCheapest$136Average$269FlexibilityNo cancel feeOn-time75%
SouthwestCheapest$196Average$316FlexibilityNo cancel feeOn-time63%

100% Free

Cheapflights is completely free to use, so you can start saving the moment you arrive.

Book with Flexibility

Our users can plan ahead with confidence and find flights with no change fees

Travel Smart

Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.