SEA - ONT

C$ 168 Find Cheap Flights from Seattle to Ontario – Compare and Save

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 27/8. 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, 0 bags

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Everything you should know

Cheapest round-trip
C$ 252
Typical prices: C$ 252-C$ 447
Frontier
Sun 23/8Sun 30/8
SEA - ONT • Direct
Cheapest one-way flights
C$ 168
Typical prices: C$ 197-C$ 349
Alaska Airlines
Thu 27/8
SEA - ONT • 1 stop
Advice from real travellers
AI-powered summary based on content written by KAYAK users. AI can make mistakes.
At SeaTac, free SpotSaver appointments can speed security before Ontario flights.
For Hawaiian, allow extra time for bag drop and the longer walk to the gate.
User tips
User tips
User tips
User tips
Top airlines
Cheapest • from C$ 252 (round-trip)
Best reviews • 7.9 score
Airline reviews
Airline reviews
+1
+1
Airline reviews
Airline reviews
+1
Direct flights
You can fly direct with Alaska Airlines, Delta, and Frontier. Average duration is 2h 48m
Direct flights
Direct flights
+1
+1
Direct flights
Direct flights
+1
When to book
in advance
Our data shows that travellers who book at least 4 weeks in advance save around 41% compared to booking last minute.
Insights
Insights
Insights
Insights
When to travel
Cheapest • 31% price drop
Most popular
Good to know
Good to know
+1
+1
Good to know
Good to know
+1
Start a new search
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We hope you love your trip to Ontario!
Flight Deals
Booking Insights
Flight 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

Sun, 23 Aug - Sun, 30 Aug
Frontier Logo
11:54 a.m. - 2:45 p.m.
SEA
-
ONT
2h 51mdirect
Frontier Logo
5:17 p.m. - 8:02 p.m.
ONT
-
SEA
2h 45mdirect
C$ 252Frontier
Sat, 5 Sep - Mon, 7 Sep
Frontier Logo
11:54 a.m. - 2:45 p.m.
SEA
-
ONT
2h 51mdirect
Frontier Logo
5:17 p.m. - 8:02 p.m.
ONT
-
SEA
2h 45mdirect
C$ 252Frontier
Sun, 30 Aug - Fri, 4 Sep
Frontier Logo
11:54 a.m. - 2:45 p.m.
SEA
-
ONT
2h 51mdirect
Frontier Logo
5:17 p.m. - 8:02 p.m.
ONT
-
SEA
2h 45mdirect
C$ 271Frontier
Sat, 5 Sep - Tue, 8 Sep
Frontier Logo
9:36 p.m. - 8:03 a.m.
SEA
-
ONT
10h 27m
1 stop
Frontier Logo
4:44 p.m. - 7:33 p.m.
ONT
-
SEA
2h 49mdirect
C$ 273Frontier
Fri, 28 Aug - Tue, 1 Sep
Multiple Airlines Logo
10:00 a.m. - 4:10 p.m.
SEA
-
ONT
6h 10m
1 stop
Multiple Airlines Logo
4:44 p.m. - 7:33 p.m.
ONT
-
SEA
2h 49mdirect
C$ 275Multiple Airlines
Tue, 18 Aug - Sun, 23 Aug
Multiple Airlines Logo
11:54 a.m. - 2:45 p.m.
SEA
-
ONT
2h 51mdirect
Multiple Airlines Logo
7:12 a.m. - 12:50 p.m.
ONT
-
SEA
5h 38m
1 stop
C$ 289Multiple Airlines
Thu, 13 Aug - Fri, 21 Aug
Alaska Airlines Logo
8:33 p.m. - 11:11 p.m.
SEA
-
ONT
2h 38mdirect
Alaska Airlines Logo
7:59 p.m. - 10:41 p.m.
ONT
-
SEA
2h 42mdirect
C$ 306Alaska Airlines
Thu, 13 Aug - Thu, 20 Aug
Alaska Airlines Logo
8:33 a.m. - 11:14 a.m.
SEA
-
ONT
2h 41mdirect
Alaska Airlines Logo
7:59 p.m. - 10:41 p.m.
ONT
-
SEA
2h 42mdirect
C$ 306Alaska Airlines
Fri, 14 Aug - Sun, 16 Aug
Alaska Airlines Logo
1:50 p.m. - 4:30 p.m.
SEA
-
ONT
2h 40mdirect
Alaska Airlines Logo
5:26 p.m. - 8:06 p.m.
ONT
-
SEA
2h 40mdirect
C$ 306Alaska Airlines
Sun, 16 Aug - Wed, 26 Aug
Multiple Airlines Logo
12:19 p.m. - 3:14 p.m.
SEA
-
ONT
2h 55mdirect
Multiple Airlines Logo
7:12 a.m. - 12:50 p.m.
ONT
-
SEA
5h 38m
1 stop
C$ 317Multiple Airlines
Booking Insights

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.

How much is a round-trip flight from Seattle to Ontario?

This analysis is based on the cheapest round-trip price found on KAYAK in the last 12 months by searching for a flight from Seattle to Ontario departing in August.

Flight prices are typical for this route right now.

Flights to Ontario from Seattle usually cost between C$ 252 and C$ 447 in August.
The lowest price found in the past 5 days was C$ 252 on Frontier (23 Aug–30 Aug).

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 Fridays if you are looking for the best rates. For your return to Seattle, you’ll find the best rates on Tuesdays and the most expensive ones on Saturdays.

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 October, where tickets cost C$ 268 (return) on average. On the other hand, the most expensive months are February and July, where the average cost of round-trip tickets is C$ 527 and C$ 458 respectively.

Can I save money by flying with a layover from Seattle to Ontario?

The average round-trip price for all non-stop flights, flights with one layover, and flights with two layovers for the route found by users searching on KAYAK in the last 2 weeks.

No, with an average price for the route of C$ 290, prices are generally cheapest when you fly direct.

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 4 weeks before departure, which saves you about 41% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 5 weeks before departure.

Good to know

Low season

July

Cheapest flight

C$ 168
Best time to beat the crowds but there is an average 18% increase in price.
Most popular time to fly and prices are also 15% lower 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 Airlines
SEA
-
ONT
Jun 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 Airlines
SEA
-
ONT
Oct 2024
SeaTac lets you make an appointment to get through security. SpotSaver. No cost. Online.

FAQs for booking flights from Seattle to Ontario

  • What is the cheapest flight from Seattle to Ontario?

    In the last 5 days, the lowest price for a flight from Seattle to Ontario was C$ 168 for a one-way ticket and C$ 252 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, Delta, American Airlines, Hawaiian Airlines, and JetBlue offer inflight Wi-Fi service on the Seattle to Ontario flight route.

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

    The Airbus A321neo 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 is the only airline alliance operating flights between Seattle and Ontario.

  • 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$ 446 and an overall rating of 7.9, Alaska Airlines is the most popular choice. Frontier is also a great choice for the route, with an average price of C$ 312 and an overall rating of 5.6.

  • 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

  • Looking for a cheap flight? 25% of our users found flights on this route for C$ 240 or less round-trip.

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

Alaska Airlines,Delta, +1 more

Tuesday

Alaska Airlines,Delta,Frontier

Alaska Airlines,Delta, +1 more

Wednesday

Alaska Airlines,Delta,Frontier

Alaska Airlines,Delta, +1 more

Thursday

Alaska Airlines,Delta,Frontier

Alaska Airlines,Delta, +1 more

Friday

Alaska Airlines,Delta,Frontier

Alaska Airlines,Delta, +1 more

Saturday

Alaska Airlines,Delta,Frontier

Alaska Airlines,Delta, +1 more

Sunday

Alaska Airlines,Delta,Frontier

Alaska Airlines,Delta, +1 more

See more nonstop flights

Direct returns

Ontario to Seattle/Tacoma Intl

Monday

Alaska Airlines,Delta,Frontier

Alaska Airlines,Delta, +1 more

Tuesday

Alaska Airlines,Delta,Frontier

Alaska Airlines,Delta, +1 more

Wednesday

Alaska Airlines,Delta,Frontier

Alaska Airlines,Delta, +1 more

Thursday

Alaska Airlines,Delta,Frontier

Alaska Airlines,Delta, +1 more

Friday

Alaska Airlines,Delta,Frontier

Alaska Airlines,Delta, +1 more

Saturday

Alaska Airlines,Delta,Frontier

Alaska Airlines,Delta, +1 more

Sunday

Alaska Airlines,Delta,Frontier

Alaska Airlines,Delta, +1 more

See more nonstop flights

Reviews of the 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.
7.9
Alaska AirlinesOverall score based on 12718 reviews
7.0Entertainment
8.1Boarding
7.0Food
7.8Comfort
8.5Crew
Airline reviews

Hate the way they nickel and dime you on pricing. Extra for baggage, extra for a pre assigned seat. Make it one price and be done with it.

8.0 ExcellentCarol, Jul 2026
SEA - PSP
Read more Alaska Airlines reviews

Hate the way they nickel and dime you on pricing. Extra for baggage, extra for a pre assigned seat. Make it one price and be done with it.

The flight got delayed for some unknown reason to us. Then, after boarding, we stayed grounded for almost an hour without any explanation or announcement. Then, finally lifted off. When we landed and made our way to baggage claim. The luggage took 30 minutes to come! It was past midnight due to the flight being delayed and my litter children were cranky and tired! It was not a great experience. Perhaps, more explanation of what is going on with the flight would be helpful!

Loved the staff ease of flying snacks and free movies and WiFi

Flight was very warm. It felt like there was no working AC.

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.

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.

Finally get a snack n drinks! Just like the good ole days!

Seats lack shoulder and elbow room. The lady next to me was short and slightly heavy with knee problems, she kept jabbing me with her elbow while playing her game on her phone for 2 hours, the duration of the whole flight. It was frustrating and annoying! I was in the middle seat, there was no space to adjust to avoid her arm jabbing me.

overall great. However, it took about 20 minutes before I could get the wifi to connect and the flight crew skipped providing me with the snack.

This flight had the most beautiful stewardess I have seen in all my travels all over the world.

Seats were new and comfortable. Staff was fine. Missed my connection due to weather -which wasn’t their fault- but got no help at all. Gate staff sent me to customer service, which was and stayed unstaffed. Sign with QR code directed me to call or chat. Chat was useless. Call was returned after an hour. No itinerary offered by Frontier could get me home in less than 30 hours. Rebooked with another airline and got a partial refund that came to about 10 percent of what I paid to get home.

As every law enforcement agency I could imagine surrounded the plane and we didn’t disembark for 2 hours and then had to stick around for another hour to go get our personal belongings after leaving them behind and being bused away from the plane, it was scary and inconvenient. We were given no information as to why this was happening. Lack of communication with passengers was disappointing.

The ticketing agents were rude but then we had a great gate agent very nice we had to ride a buss out to where the plane was parked but it was in some back corner of the airport when we got to the plane the captain who was great btw was cleaning the plane because the same rude ticketing agent told them they we not contracted to vacuum the plane. The ride to las Vegas was fine We had a connecting flight to Dallas. The flight was fine but when we arrived in Dallas everyone who flew on any frontier airlines the picked up bags from baggage claim D15 had to wait over a hour for their bags to start we arrived at 11:30pm ish to the gate we didn't leave the baggage clamed till 12:50 am very not happy and i used to fly frontier 4 times a week for work in Denver i will not be using them again

Terrible communication with weather delay, lost baggage, near impossible to reach customer service

The crew was mostly okay. The flight attendant who answered our questions was curt and unhelpful unfortunately. He seemed upset and I understand having off days.

I was surprised that all baggage, including carry on, were charged. Each additional bag went up in cost. Really disappointed in the additional costs.

Flight was cancelled and was not able to get another flight thru Frontier. Per frontier a refund was issued but I do not see a refund on my Afirm account.

The agent at check-in was strident, unwelcoming, and condescending to customers ahead of me.

Was charged 99 dollars for a bag despite agents previously telling me it would be ok. Customer service was unhelpful

I will like you ( Frontier Airlines) to fly into LAX instead of ONT because I live in LA and the subway takes me to my house in just 15 minutes

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

Information on your arrival and departure airports