SEA - ONT

C$ 150 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 9/5. 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

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

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Everything you should know

Cheapest round-trip
C$ 205
Typical prices: C$ 397-C$ 224
Frontier
Fri 29/5Mon 1/6
SEA - ONT • 1 stop
Cheapest direct flights
C$ 271
Typical prices: C$ 432-C$ 209
Delta
Sat 2/5Tue 5/5
SEA - ONT • Direct
Advice from real travellers
AI-powered summary based on content written by KAYAK users. AI can make mistakes.
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$ 205 (round-trip)
Frontier
Best reviews • 5.7 score
Airline reviews
Airline reviews
+1
+1
Airline reviews
Airline reviews
+1
Direct flights
Every day
You can fly direct with Alaska Airlines, Delta, and Frontier. Average duration is 2h 44m
Direct flights
Direct flights
+1
+1
Direct flights
Direct flights
+1
When to book
3 weeks
in advance
Our data shows that travellers who book at least 3 weeks in advance save around 28% compared to booking last minute.
Insights
Insights
Insights
Insights
When to travel
October
Cheapest • 28% price drop
May
Most popular
Good to know
Good to know
+1
+1
Good to know
Good to know
+1
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!
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

Fri, 29 May - Mon, 1 Jun
Frontier Logo
8:20 p.m. - 3:09 p.m.
SEA
-
ONT
18h 49m
1 stop
Frontier Logo
4:04 p.m. - 7:05 p.m.
ONT
-
SEA
3h 01mdirect
C$ 205Frontier
Sat, 6 Jun - Sun, 7 Jun
Frontier Logo
11:51 a.m. - 2:35 p.m.
SEA
-
ONT
2h 44mdirect
Frontier Logo
6:00 a.m. - 10:06 a.m.
ONT
-
SEA
28h 06m
1 stop
C$ 208Frontier
Sun, 3 May - Thu, 7 May
Frontier Logo
7:12 p.m. - 7:31 a.m.
SEA
-
ONT
12h 19m
1 stop
Frontier Logo
11:36 a.m. - 10:22 a.m.
ONT
-
SEA
22h 46m
1 stop
C$ 220Frontier
Wed, 13 May - Sun, 24 May
Frontier Logo
7:50 p.m. - 10:05 a.m.
SEA
-
ONT
14h 15m
1 stop
Frontier Logo
4:04 p.m. - 7:05 p.m.
ONT
-
SEA
3h 01mdirect
C$ 240Frontier
Sat, 2 May - Thu, 7 May
Frontier Logo
7:12 p.m. - 7:26 a.m.
SEA
-
ONT
12h 14m
1 stop
Frontier Logo
4:04 p.m. - 10:22 a.m.
ONT
-
SEA
18h 18m
1 stop
C$ 249Frontier
Wed, 13 May - Wed, 20 May
Delta Logo
8:25 a.m. - 11:12 a.m.
SEA
-
ONT
2h 47mdirect
Delta Logo
5:50 p.m. - 8:50 p.m.
ONT
-
SEA
3h 00mdirect
C$ 271Delta
Wed, 13 May - Sun, 24 May
Multiple Airlines Logo
9:22 p.m. - 11:58 p.m.
SEA
-
ONT
2h 36mdirect
Multiple Airlines Logo
4:04 p.m. - 7:05 p.m.
ONT
-
SEA
3h 01mdirect
C$ 281Multiple Airlines
Sat, 9 May - Thu, 14 May
Alaska Airlines Logo
7:05 a.m. - 9:45 a.m.
SEA
-
ONT
2h 40mdirect
Alaska Airlines Logo
4:03 p.m. - 6:52 p.m.
ONT
-
SEA
2h 49mdirect
C$ 285Alaska Airlines
Sat, 9 May - Sun, 10 May
Delta Logo
9:45 a.m. - 12:35 p.m.
SEA
-
ONT
2h 50mdirect
Delta Logo
6:45 a.m. - 9:49 a.m.
ONT
-
SEA
3h 04mdirect
C$ 286Delta
Sat, 9 May - Sun, 10 May
Delta Logo
7:50 p.m. - 10:34 p.m.
SEA
-
ONT
2h 44mdirect
Delta Logo
6:45 a.m. - 9:49 a.m.
ONT
-
SEA
3h 04mdirect
C$ 288Delta
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 May.

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 Saturdays and the most expensive ones on Thursdays.

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$ 257 (return) on average. On the other hand, the most expensive months are February and December, where the average cost of round-trip tickets is C$ 519 and C$ 436 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 28% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 14 weeks before departure.

Find deals

Good to know

Low seasonMarch
Cheapest flightC$ 150
Best time to beat the crowds but there is an average 8% increase in price.
Most popular time to fly and prices are also 9% 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 
Learn how KAYAK collects reviews and tips from users.
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 3 days, the lowest price for a flight from Seattle to Ontario was C$ 150 for a one-way ticket and C$ 205 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, Hawaiian Airlines, 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.

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

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

  • 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.

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 airline 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.
5.7
FrontierOverall score based on 2989 reviews
4.3Entertainment
6.6Crew
5.9Boarding
4.5Food
5.4Comfort
Airline reviews

They switched our terminal 3 times and we were delayed for four plus hours!!!

2.0 MediocreAnonymous, Apr 2026
DTW - PHX
Read more Frontier reviews

They switched our terminal 3 times and we were delayed for four plus hours!!!

It was an early flight and most people napped/slept and the crew let us which was nice.

The crew acted like they had never done this and kept barking passive aggressive orders at people. + the security line + the delay + sitting on the tarmac for 2 hours + none of the apps or signage updating with correct times

Our flight was canceled. I will never use Kayak nor Frontier for travel again. The entire experience was a headache.

Terrible. The canceled my entire flight when I requested a refund for a trip frontier canceled trip one way.

I knew going into this that Frontier, being a low cost carrier, would be pretty bare bones and charge for most extras but this was made up for by the fact that the airplane was a reasonably new Airbus, every employee was great and best of all, Everett Washington is an amazing airport - thanks Frontier for flying there!!!

i was unable to check in the flight. refund requested

I think Frontier was very good at communication. Their app worked very well. Loading was great and the flight was nice and easy.

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.

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

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

Information on your arrival and departure airports

Seattle (SEA)
Ontario (ONT)