SEA - ONT

C$ 109 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 12/10. 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
Travellers love KAYAK
41,299,237 searches in the past 7 days on KAYAK

Save 24% or moreCompare multiple travel sites with one search.

Track pricesNot ready to book? Create a price alert for when prices drop.

Free to useThere are no hidden charges or fees.

Filter your dealsChoose cabin class, free Wi-Fi and more.

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

Sat, 8 Nov - Tue, 11 Nov
Frontier Logo
12:58 p.m. - 11:50 p.m.SEA-ONT
10h 52m1 stop
Frontier Logo
6:53 a.m. - 12:13 p.m.ONT-SEA
29h 20m1 stop
C$ 200Frontier
Find Deal
Sun, 28 Sep - Sat, 11 Oct
Frontier Logo
6:12 a.m. - 7:53 a.m.SEA-ONT
25h 41m1 stop
Frontier Logo
7:04 a.m. - 7:33 a.m.ONT-SEA
24h 29m1 stop
C$ 231Frontier
Find Deal
Wed, 15 Oct - Wed, 22 Oct
Alaska Airlines Logo
9:51 a.m. - 12:37 p.m.SEA-ONT
2h 46mdirect
Alaska Airlines Logo
6:00 a.m. - 8:45 a.m.ONT-SEA
2h 45mdirect
C$ 245Alaska Airlines
Find Deal
Wed, 15 Oct - Wed, 22 Oct
Southwest Logo
10:10 a.m. - 5:00 p.m.SEA-ONT
6h 50m1 stop
Southwest Logo
3:50 p.m. - 10:45 p.m.ONT-SEA
6h 55m2 stops
C$ 251Southwest
Find Deal
Wed, 22 Oct - Mon, 27 Oct
Delta Logo
2:24 p.m. - 5:10 p.m.SEA-ONT
2h 46mdirect
Delta Logo
7:35 a.m. - 10:35 a.m.ONT-SEA
3h 00mdirect
C$ 258Delta
Find Deal
Sat, 25 Oct - Tue, 28 Oct
Southwest Logo
7:05 a.m. - 1:00 p.m.SEA-ONT
5h 55m1 stop
Southwest Logo
3:50 p.m. - 10:45 p.m.ONT-SEA
6h 55m2 stops
C$ 265Southwest
Find Deal
Thu, 23 Oct - Sun, 26 Oct
Hawaiian Airlines Logo
9:25 p.m. - 12:03 a.m.SEA-ONT
2h 38mdirect
Hawaiian Airlines Logo
6:00 a.m. - 8:50 a.m.ONT-SEA
2h 50mdirect
C$ 272Hawaiian Airlines
Find Deal
Fri, 24 Oct - Mon, 27 Oct
Delta Logo
7:55 p.m. - 10:41 p.m.SEA-ONT
2h 46mdirect
Delta Logo
7:35 a.m. - 10:35 a.m.ONT-SEA
3h 00mdirect
C$ 275Delta
Find Deal
Fri, 27 Feb - Sat, 28 Feb
Alaska Airlines Logo
11:20 a.m. - 5:42 p.m.SEA-ONT
6h 22m1 stop
Alaska Airlines Logo
6:00 p.m. - 10:24 p.m.ONT-SEA
4h 24m1 stop
C$ 285Alaska Airlines
Find Deal
Fri, 7 Nov - Sat, 8 Nov
Hawaiian Airlines Logo
8:55 p.m. - 11:32 p.m.SEA-ONT
2h 37mdirect
Hawaiian Airlines Logo
6:00 a.m. - 8:50 a.m.ONT-SEA
2h 50mdirect
C$ 307Hawaiian Airlines
Find Deal

Everything you should know

Our travellers' advice
AI-generated summary based on content written by KAYAK users
SeaTac offers SpotSaver for faster security checks.
Allow extra time for bag drop with Hawaiian Airlines.
User tips
User tips
User tips
User tips
Top airlines
Frontier
Cheapest • from C$ 200 (round-trip)
Alaska Airlines
Best reviews • 8.0 score
Airline reviews
Airline reviews
+1
+1
Airline reviews
Airline reviews
+1
When to book
3 weeks
in advance
Our data shows that travellers who book at least 3 weeks in advance save around 32% compared to booking last minute.
Insights
Insights
Insights
Insights
When to travel
October
Cheapest • 18% price drop
December
Most popular
Good to know
Good to know
+1
+1
Good to know
Good to know
+1
Cheapest round-trip
C$ 200
Overall average: C$ 300
Frontier
Sat 8/11Tue 11/11
SEA - ONT • 1 stop
Cheapest direct flights
C$ 245
Typical prices: C$ 140-356
Alaska Airlines
Wed 15/10Wed 22/10
SEA - ONT • Direct
Start a new search
KAYAK searches hundreds of sites at once to find you the best travel deals.
We hope you love your trip to Ontario!
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.

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 Monday and avoid Sundays 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 October, where tickets cost C$ 245 (return) on average. On the other hand, the most expensive months are December and July, where the average cost of round-trip tickets is C$ 363 and C$ 355 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 3 weeks before departure, which saves you about 32% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 8 weeks before departure.

Good to know

Low seasonJanuary
Cheapest flightC$ 109
Best time to beat the crowds (11% less expensive on average)
Most popular time to fly (22% 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

  • 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$ 79 for a one-way ticket and C$ 145 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 Boeing 737-800 Passenger/BBJ2 (winglets) 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$ 306 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$ 259 and an overall rating of 5.8.

  • 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$ 286 or less one-way and C$ 259 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.
8.0
Alaska AirlinesOverall score based on 10000 reviews
7.8Comfort
7.1Food
8.5Crew
7.0Entertainment
8.1Boarding
Airline reviews

All flights were on time. No crowded and had empty seats. All flight attendents were great.

10.0 ExcellentAnonymous, Sep 2025SEA - SAN
Read more Alaska Airlines reviews

All flights were on time. No crowded and had empty seats. All flight attendents were great.

Seattle airport is a mess. New bag tag system has potential, but you need more signage to guide passengers through the process as to where to go next. Told to go in one direction and then met with a very rude agent when we did. He blamed his attitude on all the folks flying over labor day that were paying his salary. Gate area for D3 is a mess compared to the North terminal. Overall Alaska is number 1 in my book.

The airline staff was great! The best safety review ive ever had!

Agent boarding us in San Diego lectured me on showing up on time for the flight, and said that if I had been three minutes later, he would have denied myself and my wife boarding. Our trusted traveler numbers were not in the system, even though I entered them when I bought the tickets. Our food orders were not in the system, even though I entered them prior to the flight. My wife requires a wheelchair, and that was delayed on both flights.

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

My 1.5 hr flight was 5.5 hrs delayed. We switched gates twice. We planed and deplaned once. Three total planes, two had “mechanical issues.” None of this even makes sense as the original plane was sitting at the gate since yesterday evening. Then when the second plane was finally brought to the gate from the hangar, it too needed repair. Don’t worry. They gave us a $12 foot voucher. All other flights in the same area of the terminal were hours delayed. It was an actual nightmare. This was after a few hours delay on my first flight a few days ago. And I thought that was bad.

I was in the middle seat in the last row but that wasn’t their fault. It is why I rated the flight as mediocre, also the landing was a little rough. The good was really good. The self service luggage belt at SEATAC stopped working right when I reached it. I was literally placing my bag on the small belt when the main belt stopped. I understand that it wasn’t just Alaska but the entire side of the terminal. It took the agents about 20 minutes to arrive at a game plan and it certainly wasn’t flawless but they arranged for our luggage to be taken to the plane the old fashioned way by hand. Understandably, the plane was late in leaving. The flight took the proper amount of time and instead of arriving at OAK at 1:45, we got there at 2:30. I took my time getting to baggage claim because I knew it would be late if it was there at all. Sure enough it wasn’t but there was an agent there to greet me and inform me about my luggage. Long story longer, they delivered my luggage to where I was staying which was an hour away from the airport. Alaska has instituted a delivery type tracking system through my email that kept me informed of where my luggage was the whole time. WELL DONE!!

I am always uncomfortable about the boarding process. I think every airlines has their own procedures for boarding but all of their procedures are inconvenient because it takes too much time to board. If you board people from back seat to front, I think you can reduce the time to boarding.

There was a delay, then we were boarded, then deboarded, then waited another hour for a new flight, then boarded again and arrived 2 hours later than expected while traveling with 3 young children.

Original flight was canceled, and the automatically booked second flight was immediately delayed. I arrived about 4 hours later than planned with only a $12 meal voucher that didn't fully cover a sandwich at airport prices.

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.

Finally a Frontier on time and efficient. I've had problems before with your airline, but this time everything went fine.

The experience was good. No frills but I got there safe and sound and on time.

Great for the price. No wifi or entertainment, but gate agents and crew were fantastic and we boarded quickly and left on time.

sluggish boarding and arrival procedures, fake nice flight attendants, and lots of delays.

Disaster. They lied every step of the way. We ended up being delayed due to crew and then allegedly abandoned the flight because of a curfew at LGA. No rebooking to LGA at any reasonable time. No hotel. No meal vouchers. Had to sleep in the airport and fly to Newark instead. Will never fly Frontier again.

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.

Decent clean onboard experience. Okay discount airline experience. Unfortunately, any customer service interactions are difficult and unhelpful. There is no service. Also, a premium seat only gets you premium boarding if you line up first. Once they start general boarding you must go to the back of the line. Not very premium

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

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

Information on your arrival and departure airports

Not what you’re looking for? Find thousands of other hotels, flights, car rentals and package deals with KAYAK.