SEA - ONT

C$ 113 Find Cheap Flights from Seattle to Ontario

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Seattle to Ontario departing on 8/7. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult
1 adult, Economy

KAYAK searches hundreds of travel sites at once for deals on flights to Ontario

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Seattle to Ontario, as well as popular online travel agencies
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Seattle to Ontario, as well as popular online travel agencies
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Flights Deals

Cheap Flights from Seattle to Ontario (SEA-ONT)

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Seattle to Ontario that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from Seattle to Ontario

Thu, 17 Jul - Sun, 20 Jul
Frontier Logo
1:42 p.m. - 4:36 p.m.SEA-ONT
2h 54mdirect
Frontier Logo
10:03 a.m. - 12:53 p.m.ONT-SEA
2h 50mdirect
C$ 213Frontier
Find Deal
Tue, 15 Jul - Tue, 15 Jul
Alaska Airlines Logo
8:27 a.m. - 11:05 a.m.SEA-ONT
2h 38mdirect
Alaska Airlines Logo
2:22 p.m. - 4:59 p.m.ONT-SEA
2h 37mdirect
C$ 234Alaska Airlines
Find Deal
Tue, 22 Jul - Tue, 29 Jul
Delta Logo
2:20 p.m. - 5:16 p.m.SEA-ONT
2h 56mdirect
Delta Logo
2:14 p.m. - 5:00 p.m.ONT-SEA
2h 46mdirect
C$ 240Delta
Find Deal
Tue, 15 Jul - Tue, 15 Jul
Alaska Airlines Logo
5:25 a.m. - 9:23 a.m.SEA-ONT
3h 58m1 stop
Alaska Airlines Logo
12:00 p.m. - 2:38 p.m.ONT-SEA
2h 38mdirect
C$ 246Alaska Airlines
Find Deal
Thu, 21 Aug - Tue, 26 Aug
Southwest Logo
6:30 a.m. - 12:40 p.m.SEA-ONT
6h 10m1 stop
Southwest Logo
9:25 a.m. - 2:10 p.m.ONT-SEA
4h 45m1 stop
C$ 268Southwest
Find Deal
Thu, 21 Aug - Tue, 26 Aug
Southwest Logo
11:50 a.m. - 9:05 p.m.SEA-ONT
9h 15m2 stops
Southwest Logo
6:30 a.m. - 3:05 p.m.ONT-SEA
8h 35m1 stop
C$ 274Southwest
Find Deal
Sun, 13 Jul - Wed, 16 Jul
Delta Logo
7:30 a.m. - 10:25 a.m.SEA-ONT
2h 55mdirect
Delta Logo
5:59 p.m. - 8:45 p.m.ONT-SEA
2h 46mdirect
C$ 295Delta
Find Deal
Sun, 27 Jul - Wed, 6 Aug
Delta Logo
7:30 a.m. - 10:25 a.m.SEA-ONT
2h 55mdirect
Delta Logo
6:25 a.m. - 9:13 a.m.ONT-SEA
2h 48mdirect
C$ 301Delta
Find Deal
Thu, 4 Sep - Tue, 9 Sep
United Airlines Logo
7:00 a.m. - 12:13 p.m.SEA-ONT
5h 13m1 stop
United Airlines Logo
6:50 p.m. - 10:59 p.m.ONT-SEA
4h 09m1 stop
C$ 335United Airlines
Find Deal
Wed, 9 Jul - Tue, 15 Jul
United Airlines Logo
5:10 a.m. - 12:14 p.m.SEA-ONT
7h 04m1 stop
United Airlines Logo
1:19 p.m. - 6:58 p.m.ONT-SEA
5h 39m1 stop
C$ 363United Airlines
Find Deal
Expert advice

Expert advice for your flight from Seattle to Ontario

 
Snippets provided in this section are AI-generated based on a summarisation of KAYAK-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.
KAYAK teamed up with top travel experts to share the best tips for your journey.
Airlines
Delta

Delta's Comfort Plus offers extra legroom and priority boarding, enhancing short-haul comfort.


Enjoy free Wi-Fi on Delta flights for SkyMiles members, perfect for staying connected.

Read more about Deltaby Stefanie Waldek
Frontier

Frontier's Economy Bundle includes a carry-on and seat choice, ideal for budget travelers.


Consider Premium Bundle for priority boarding and extra legroom, just $20 more than Economy.

Read more about Frontierby Stefanie Waldek
Alaska Airlines

Alaska's 20-minute bag guarantee ensures quick baggage claim or compensation.


Alaska's Premium Class offers extra legroom and free drinks on flights over 350 miles.

Airports
SEA

Use the SEA Spot Saver for free expedited security screening from 4 a.m. to 10 p.m. at Checkpoints 2, 3, and 5.

Read more about SEAby Harriet Baskas
ONT

Take the Metrolink San Bernardino Line to Rancho Cucamonga Station, then the ONT Connect Shuttle to reach ONT easily.

Read more about ONTby Jennifer Simonson
Our travel experts
Stefanie Waldek

Stefanie Waldek

Expert on Delta and Frontier

Stefanie Waldek

Stefanie Waldek

Stefanie Waldek is a freelance space, travel, and design writer based in Saratoga Springs, NY. Her words have appeared in Space.com, Travel + Leisure, Condé Nast Traveler, Architectural Digest, and House Beautiful, among other publications. An expert in aviation and expedition cruising, Stefanie is frequently up in the air or on the sea, likely en route to Antarctica or the Arctic.

Read more
Harriet Baskas

Harriet Baskas

Expert on Alaska Airlines and SEA

Harriet Baskas

Harriet Baskas

Harriet is an award-winning journalist who is happiest in an airport or an unusual museum. Her stories about airports, air travel, and the business of travel have appeared on NBC News, CNBC, USA TODAY, The Points Guy and other outlets. She is the creator of the StuckatTheAirport.com blog and the author of nine books. When not out on the road or exploring the latest airport amenities, she’s home in Seattle getting ready for the next adventure.

Read more
Jennifer Simonson

Jennifer Simonson

Expert on ONT

Jennifer Simonson

Jennifer Simonson

Jennifer Simonson is driven by her lifelong commitment to exploring the globe. Her insatiable curiosity had led her to immerse herself into diverse locations like Oklahoma City and Pismo. Her hotel recommendations are the result of the myriad hotels she's stayed at across her travels. Along her journey, she cherishes engaging conversations with locals, indulging in the finest ice cream, trying her hand at surfing, and embarking on nature-filled hikes.

Read more
Useful Info

KAYAK's insights & trends for Seattle to Ontario flights

Get data-powered insights and trends into flights from Seattle to Ontario to help you find the cheapest flights, the best time to fly and much more.

What’s the cheapest day of the week to fly from Seattle to Ontario?

The average price of all round-trip flights from Seattle to Ontario clicked on KAYAK for each day over the last 12 months.

When flying from Seattle to Ontario, you should consider leaving on a Saturday and avoid Mondays if you are looking for the best rates. For your return to Seattle, you’ll find the best rates on Saturdays and the most expensive ones on Wednesdays.

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

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from Seattle to Ontario, removes the top 0.1% to account for outliers, and then takes the median of all values for each month.

The cheapest month for flights from Seattle to Ontario is September, where tickets cost C$ 179 (return) on average. On the other hand, the most expensive months are December and May, where the average cost of round-trip tickets is C$ 357 and C$ 323 respectively.

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

To calculate weekly average prices, KAYAK takes all prices for each week before departure over the last year for round-trip flights from Seattle to Ontario, removes the top 0.1% to account for outliers, and then takes the average of all the values for each week.

To get a below average price on the flight from Seattle to Ontario, you should book around 2 weeks before departure. For the absolute cheapest price, our data suggests you should book 11 weeks before departure.


Good to know

Low seasonJanuary
High seasonJuly
Cheapest flightC$ 113
Best time to beat the crowds (7% less expensive on average)
Most popular time to fly (6% more expensive on average)
Flight from Seattle to Ontario

When to book flights from Seattle to Ontario

Are your dates flexible? Find out the best times to travel from Seattle to Ontario based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated round-trip price
KAYAK looks at all historical flight data for each date to provide a predicted price for one-way trips or round-trips with a duration up to 40 days. While we try to provide actual minimum prices for each date, some prices are predictions and actual prices may differ.

Flights from Seattle to Ontario: the best tips from KAYAK users' own experiences

Insights shared by verified travellers who flew the route from Seattle to Ontario 
Verified travelerFlew with Hawaiian AirlinesSEA-ONTJun 2025
Make sure to be there on time because the bag drop off can be a little complicated and it takes quite some time to get to the gate.
Verified travelerFlew with Alaska AirlinesSEA-ONTOct 2024
SeaTac lets you make an appointment to get through security. SpotSaver. No cost. Online.

FAQs for booking flights from Seattle to Ontario

  • Does SEA have facilities for disabled traveling passengers?

    You can use the sunflower lanyard program when you're departing from Seattle to Ontario and need assistance at the SEA airport. This program is available to passengers with hidden disabilities who need extra help with check-ins, security screening, and carrying luggage. If you'd like to use the service, you can request sunflower lanyards at the pre-security information desk, between checkpoints 3 and 4, or the post-security information desk in Concourse A.

  • Does Ontario Airport have pet relief areas?

    Once you land in Ontario, you can use the pet relief areas inside and outside the terminals if your pet needs relief. The outside areas are at the far end of the terminal buildings. The areas inside are near gates 210 and 410. The relief areas have waste disposal bags and bins, which you can use to clean after your pet.

  • Is there public transportation available from Ontario Airport?

    Ontario has a well-designed bus and rail transportation service. If you'd like public transport from ONT, you can use the public buses boarded at terminal 2. The buses are available every 20min.

  • Does Ontario Airport have a USO Military Lounge?

    The USO military lounge is a space for military members and their families to sit and relax. Families can access free internet services, entertainment, and food and drinks. The ONT USO lounge is across parking lot F.

  • What is the cheapest flight from Seattle to Ontario?

    In the last 3 days, the lowest price for a flight from Seattle to Ontario was C$ 83 for a one-way ticket and C$ 157 for a round-trip.

  • Which airports will I be using when flying from Seattle to Ontario?

    Seattle airport is called Seattle/Tacoma Intl and the only airport in Ontario is Ontario.

  • Which airlines offer Wi-Fi service onboard planes from Seattle to Ontario?

    Alaska Airlines, Hawaiian Airlines, Delta, and American Airlines offer inflight Wi-Fi service on the Seattle to Ontario flight route.

  • Which aircraft models fly most regularly from Seattle to Ontario?

    The Airbus A320neo is the aircraft model that flies most regularly on the Seattle to Ontario flight route.

  • Which airline alliances offer flights from Seattle to Ontario?

    oneworld, and SkyTeam are the airline alliances operating flights between Seattle and Ontario, with SkyTeam being the most commonly used for this route.

  • On which days can I fly direct from Seattle to Ontario?

    There are direct flights from Seattle to Ontario on a daily basis.

  • Which is the best airline for flights from Seattle to Ontario, Alaska Airlines or Frontier?

    The two airlines most popular with KAYAK users for flights from Seattle to Ontario are Alaska Airlines and Frontier. With an average price for the route of C$ 300 and an overall rating of 8.0, Alaska Airlines is the most popular choice. Frontier is also a great choice for the route, with an average price of C$ 158 and an overall rating of 5.9.

  • How does KAYAK find such low prices on flights from Seattle to Ontario?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from Seattle to Ontario.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from Seattle to Ontario?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to Ontario from Seattle is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from Seattle to Ontario?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly to Ontario with an airline and back to Seattle with another airline.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from Seattle to Ontario?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying to Ontario from Seattle up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

KAYAK’s top tips for finding a cheap flight from Seattle to Ontario

  • Seattle Airport (SEA) has made it easy for travelers departing from the airport and are interested in parking their cars. The airport has a pre-booking system that allows travelers to book a parking spot before arriving at the airport. You can use this feature through the airport's website.
  • When departing to Ontario from Seattle Airport, saving time at TSA screening is a priority. Fortunately, SEA has a service that allows passengers to reserve a screening spot through the SEA Spot Saver. Reservations and walk-in appointments for departing passengers are available from 5 am to 1 pm every day at checkpoints 2, 3, and 5 for all airlines.
  • There are various transport options when you land at Ontario Airport (ONT). You can pick up a rental car from the rental car facility. ONT has airport shuttles that ferry passengers from the terminals to the on-airport rental car center. The shuttles run every 5-20min and are at the Terminal Islands of terminals 2 and 4.
  • Waiting for your flight to Ontario at the Seattle Airport can be overwhelming. You can stay in the sensory room if you need a calming environment to minimize anxiety. The room is at the train level of the A gates STS Station.
  • Every day, people face life challenges. The busyness at the airport, waiting for a flight, going through security, and checking in can add to the stress. Seattle Airport has realized this and has a beautiful therapy dogs service. The airport has partnered with Pet Partners program, where Pet Partners and their trained animals offer animal therapy at the airport. A friendly dog face or hug goes a long way to reducing stress.

Prefer to fly direct from Seattle to Ontario?

 
Direct data is based off flight results for the next 60 days. Find direct flights from all airlines flying direct from Seattle/Tacoma Intl to Ontario.
Find which airlines fly direct from Seattle/Tacoma Intl Airport to Ontario Airport, which days they fly and book direct flights.

Direct departures

Seattle/Tacoma Intl to Ontario

Monday

Alaska Airlines,Delta,Frontier, +8 more

Alaska Airlines,Delta, +9 more

Tuesday

Alaska Airlines,Delta,Frontier, +7 more

Alaska Airlines,Delta, +8 more

Wednesday

Alaska Airlines,Delta,Frontier, +8 more

Alaska Airlines,Delta, +9 more

Thursday

Alaska Airlines,Delta,Frontier, +7 more

Alaska Airlines,Delta, +8 more

Friday

Alaska Airlines,Delta,Frontier, +8 more

Alaska Airlines,Delta, +9 more

Saturday

Alaska Airlines,Delta,Frontier, +8 more

Alaska Airlines,Delta, +9 more

Sunday

Alaska Airlines,Delta,Frontier, +8 more

Alaska Airlines,Delta, +9 more

See more nonstop flights

Direct returns

Ontario to Seattle/Tacoma Intl

Monday

Alaska Airlines,Delta,Frontier, +8 more

Alaska Airlines,Delta, +9 more

Tuesday

Alaska Airlines,Delta,Frontier, +7 more

Alaska Airlines,Delta, +8 more

Wednesday

Alaska Airlines,Delta,Frontier, +8 more

Alaska Airlines,Delta, +9 more

Thursday

Alaska Airlines,Delta,Frontier, +7 more

Alaska Airlines,Delta, +8 more

Friday

Alaska Airlines,Delta,Frontier, +8 more

Alaska Airlines,Delta, +9 more

Saturday

Alaska Airlines,Delta,Frontier, +8 more

Alaska Airlines,Delta, +9 more

Sunday

Alaska Airlines,Delta,Frontier, +8 more

Alaska Airlines,Delta, +9 more

See more nonstop flights

Top airlines flying from Seattle to Ontario

 
See real verified KAYAK customer reviews for airlines flying from Seattle to Ontario. Airline scores are aggregated from all reviews left by passengers on KAYAK after flying with an airline. KAYAK doesn’t show reviews that are older than 5 years. Learn how KAYAK collects reviews.
Need help choosing which airline to fly with from Seattle to Ontario? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
8.0
Alaska AirlinesOverall score based on 10000 reviews
7.1Food
8.1Boarding
7.8Comfort
8.5Crew
7.1Entertainment
Airline reviews

Both flights were delayed going to our destination and leaving, and communication about the delays was not great by the airlines, now the crews were phenomenal and great to be around!!

6.0 GoodAnna, Jun 2025SEA - BUR
Read more Alaska Airlines reviews

Both flights were delayed going to our destination and leaving, and communication about the delays was not great by the airlines, now the crews were phenomenal and great to be around!!

Delayed. It's not our first flight with them either, it's actually our 3rd and all 3 were delayed by hours each time. It was a myriad of delays. On one flight we boarded after being delayed for a little over an hr, only to be told we were going to sit in the plane for another hour before departing. Once landed, we waited another 40ish min to get to our gate. On another flight, flight was delayed just under 3 hrs but atleast we got to wait it out at the airport terminal. Its just a bad experience overall flying with Alaska Airlines.

It is very bad they do not give you money back

The only problem was the time delay. Kudos to the counter agent in Seattle. Very helpful and gracious.

Quick and easy check-in. Love how technology has helped speed up the flying process. Smooth flight to a Seattle and back. 10/10

Need to get on train for second flight it’s much nicer when all the gates are together for obvious reasons

Cramped, crowded aircraft. Poorly organized boarding. Tasteless crackers to eat. 40 minutes late. A standard US air travel experience.

Flight was over an hour late, and we got notified every 15 minutes, beginning right at boarding, that it would only be 15 more minutes until we finally left about 75 minutes late. Of course, no compensation was offered.

I needed to board early and that was no problem. The snack was just ok. Alaska is an EXCELLENT airlines . . . luggage fast and easy.

Alaska Airlines needs more bag tag kiosks and bag check-in stations in Seattle. A single entry point for the bag tag kiosks would be helpful. This alleviates lines forming at each individual kiosk, which causes traffic jams for people passing through.

Since you have to pay for overhead bags then they shouldn't be running out of space and asking individuals who paid to remove stuff from the overhead

Cancelled flight after I arrived at airport after 75 min drive and parking. Next flight was 4 days in the future. Had to scramble and buy a much more expensive flight on another carrier.

Book with frontier airlines with the mentality that they'll cancel your flight, kick you off and lose your luggage. Anything besides that is a win. Compare prices with other airlines (to include luggage) and if frontier is still worth it, book it but know all of their policies.

You get what you pay for nothing essentially but a hard uncomfortable seat that doesn’t recline and kids screaming all around you and chaotic boarding and limited check bag weight allowance when compared to other airlines

I never got to experience the flight because they delayed my first flight and I missed this one. Then Frontier didn't want to help me rebook a flight to get me to my final destination.

Plane was down graded and I lost my uncharged exit row with more leg room. No mention or offer of refund from podium. Flight attendant was nice to explain this happens often and that I could request a refund via online form submission. I did this and have heard nothing back.

Horrendous. I do not recommend Frontier. The passengers lack manners and decency, and the flight attendants lack professionalism. If I wasn’t in a bind to fly with 48 hours notice for a job interview, I would not have selected a flight with Frontier and I never plan to fly with them in the future.

The seats were hard molded plastic covered in plastic vinyl. And the scam to charge people extra to sit together. Don’t they know we can just ask someone to trade seats. And watching the staff separate young children from parents… super classy. We had to guilt them into offering up our seats. This companies policies suck. Don’t give them your money.

I’ve never traveled on Frontier before. If you want basic, no frills, friendly service at great prices then give them a fly!

i was denied boarding, even though i had an assigned seat, checked in on line and was at airport early. Then they refused to fully refund the the fair and replacement fair because they claimed it was "no show/denied boarding". I will never fly this airline again

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

Information on your arrival and departure airports

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