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Cheap flights from Seattle to Ontario from C$ 97

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 10/2. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — ONT
11 Jan — 18 Jan1
1 adult
1 adult, Economy, 0 bags

Cheapflights Tip: The best prices from Seattle/Tacoma Intl to Ontario are usually found in October or March, booked 51 days in advance, depart on a Saturday or Monday and return on a Friday

Cheap flight deals from Seattle to Ontario

Enter your travel dates to find the best prices.

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 12 December 2025.

Wed 31/121:25 p.m.SEA - ONT
1 stop10h 34mFrontier
Mon 5/12:45 p.m.ONT - SEA
Nonstop2h 53mFrontier
Deal found 9/12C$ 215
Wed 31/129:35 p.m.SEA - ONT
Nonstop2h 39mAlaska Airlines
Mon 5/16:00 a.m.ONT - SEA
Nonstop2h 57mAlaska Airlines
Deal found 9/12C$ 251
Tue 30/1211:15 p.m.SEA - ONT
1 stop24h 44mAlaska Airlines
Thu 8/14:03 p.m.ONT - SEA
Nonstop2h 51mAlaska Airlines
Deal found 9/12C$ 263
Tue 30/1211:06 a.m.SEA - ONT
Nonstop2h 36mFrontier
Mon 5/12:45 p.m.ONT - SEA
Nonstop2h 53mFrontier
Deal found 9/12C$ 272
Mon 29/1211:06 a.m.SEA - ONT
Nonstop2h 36mFrontier
Mon 5/12:45 p.m.ONT - SEA
Nonstop2h 53mFrontier
Deal found 9/12C$ 301
Mon 29/1211:06 a.m.SEA - ONT
Nonstop2h 36mFrontier
Wed 7/17:00 a.m.ONT - SEA
1 stop28h 21mFrontier
Deal found 12/12C$ 334

Find 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 12 December 2025.

Round-trip from

C$ 177

One-way from

C$ 97

Popular in

December

Cheapest in

October

Average price

C$ 410
Alaska Airlines
  • Alaska Airlines
  • 10/1-17/1
  • Nonstop
  • 5h 28m total
  • Seattle to Ontario
Search Deals
Delta
  • Delta
  • 10/2
  • Nonstop
  • 2h 41m total
  • Seattle to Ontario
Search Deals
Highest demand for flights based on searches. 11% potential increase in price (C$ 56 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease (C$ 13 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in December 2025
Search Deals

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 629,999 searches. Data last updated 12 December 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

Sat 14/3

7:50 p.m.-10:33 p.m.

Nonstop2h 43m

Ontario

Thu 26/3

11:59 a.m.-2:55 p.m.

Nonstop2h 56m

C$ 218

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sat 3/1

7:20 a.m.-10:00 a.m.

Nonstop2h 40m

Ontario

Sat 10/1

4:03 p.m.-6:54 p.m.

Nonstop2h 51m

C$ 218

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Mon 16/3

2:30 p.m.-5:13 p.m.

Nonstop2h 43m

Ontario

Thu 26/3

11:59 a.m.-2:55 p.m.

Nonstop2h 56m

C$ 218

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Wed 18/3

8:31 a.m.-11:19 a.m.

Nonstop2h 48m

Ontario

Thu 26/3

11:59 a.m.-2:55 p.m.

Nonstop2h 56m

C$ 218

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Wed 18/3

8:31 a.m.-11:19 a.m.

Nonstop2h 48m

Ontario

Fri 27/3

5:09 p.m.-12:03 a.m.

1 stop6h 54m

C$ 232

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sat 14/3

7:50 p.m.-10:33 p.m.

Nonstop2h 43m

Ontario

Fri 27/3

5:09 p.m.-12:03 a.m.

1 stop6h 54m

C$ 232

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sun 11/1

11:15 a.m.-1:56 p.m.

Nonstop2h 41m

C$ 97

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Mon 12/1

12:31 p.m.-3:08 p.m.

Nonstop2h 37m

C$ 97

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sun 25/1

11:15 a.m.-1:56 p.m.

Nonstop2h 41m

C$ 97

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Tue 10/2

6:00 p.m.-8:36 p.m.

Nonstop2h 36m

C$ 97

Flights are sorted by cheapest round-trip flights first.

Deals found on 10/12

Showing 1-10 of 18 results
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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 5 December 2025.

Booking 51 days in advance of your planned departure date is, on average, the best time to get cheap flights from Seattle to Ontario. The general trend is that the closer you book to the departure date, the more expensive your flight will be.

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

Currently, January is the cheapest month in which you can book a flight from Seattle to Ontario (average of C$ 52). Flying from Seattle to Ontario in July is currently the most expensive (average of C$ 164). 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 12 December 2025.

One of the essential ways to save on airfare from Seattle to Ontario is to remain as flexible as possible. Flights that are at noon tend to be the most expensive. A flight in the morning could potentially save you up to 42% on airfare.

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 12 December 2025.
Read reviews from past customers who have flown Frontier from Seattle to Ontario. Users can see the overall rating for each airline as well as how each is rated in terms of entertainment options, comfort, food, crew/service, and boarding process.
Frontier
5.8
Fair
3,084 reviews
Check prices

Entertainment

4.4

Overall

5.8

Comfort

5.5

Boarding

6.0

Crew

6.6

Food

4.6

Reviews

1 / 20
4.0
Okay

Chase,Nov 2025

SLC - SEA

Worst part was not frontiers fault but being stuck on the tarmac for an hour at our arrival destination because of another planes issue and the lack of clear communication (said from the pilot himself)
Frontier
5.8
Fair
3,084 reviews
Frontier
5.8
Fair
3,084 reviews
Check prices

Entertainment

4.4

Overall

5.8

Comfort

5.5

Boarding

6.0

Crew

6.6

Food

4.6

Reviews

1 / 20
4.0
Okay

Chase,Nov 2025

SLC - SEA

Worst part was not frontiers fault but being stuck on the tarmac for an hour at our arrival destination because of another planes issue and the lack of clear communication (said from the pilot himself)

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?

    To fly from Seattle to Ontario, you need to book a flight from Seattle/Tacoma Intl (SEA) to Ontario (ONT). Nonstop flights to Ontario from Seattle/Tacoma Intl take 2h 36m on average. When it comes time to book airfare, you have a few options: there are 15 outbound flights from Seattle/Tacoma Intl to Ontario offered by 1 airline.

  • How popular is this Seattle to Ontario flight route?

    Within the past month, 14 users have taken a look at flights from Seattle/Tacoma Intl to Ontario.

  • How long is the flight from Seattle to Ontario?

    For as low as C$ 178, Alaska Airlines can have you in Ontario from Seattle in 2h 36m. Seattle and Ontario are separated by a distance of 1539 km. All flights are typically direct.

  • What is the cheapest airline to fly from Seattle to Ontario round-trip?

    Cheapflights users have booked flights from Seattle to Ontario round-trip from C$ 94. Frontier is currently priced 70% below the average price you’ll pay for this route.

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

    Looking for the most reliable airlines to get you to your destination on time? Our data shows these are most likely to get you from Seattle to Ontario on time: Virgin Atlantic (95%), SkyWest Airlines (92%), Delta (92%).

  • 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, January is the cheapest month in which you can book a flight from Seattle to Ontario (average of C$ 52). Flying from Seattle to Ontario in July is currently the most expensive (average of C$ 164). 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

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Top airline flying from Seattle to Ontario

Discover the top airline 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 629,999 searches. Data last updated 12 December 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapestC$ 94AverageC$ 258FlexibilityNo cancel feeOn-time62%
Search Frontier flights

Fly with Cheapflights

Find the best flight deals on Cheapflights, where travelers can enjoy low prices and a wide availability of flights to their desired destinations.

How does Cheapflights help users find flights from Seattle to Ontario?

When you search for this flight from Seattle to Ontario, Cheapflights searches on 900+ travel sites to save you time finding great flight deals online. Additionally, we offer filter features so you can choose a preferred cabin class or airline, see different price ranges, and much more so you can book the flight for you.

Why should you use Cheapflights to find cheap flight tickets from Seattle to Ontario?

It’s simple! Cheapflights, which is free to use for everyone, saves millions of users time and money every year by helping them find the cheapest and most suitable flights from Seattle to Ontario.

Can Cheapflights find flights from Seattle to Ontario with no change fees?

Yes! Cheapflights helps users easily find flights from Seattle to Ontario with no change fees.

Can Cheapflights notify me if prices for flights from Seattle to Ontario become cheaper?

Yes, and it’s super simple to set up. Click the bell icon next to the flight deals above and provide a valid email address to enable Price Alerts. That’s it!

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