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Cheap flights from Seattle to Ontario from C$ 167

SEA — YYZ
10 Oct — 17 Oct1
1 adult
1 adult, Economy, 0 bags

Cheap flight deals from Seattle to Ontario

Enter your travel dates to find the best prices.

Cheapest flights from Seattle to Ontario

Sat 3/107:35 p.m. -
1 stop7h 00m
Tue 6/106:55 a.m. -
2 stops14h 50m
Deal found 9/9C$ 398
Mon 28/97:35 p.m. -
1 stop7h 00m
Wed 7/101:20 p.m. -
1 stop8h 25m
Deal found 9/9C$ 418
Fri 2/107:35 p.m. -
1 stop7h 00m
Tue 6/108:15 p.m. -
1 stop25h 30m
Deal found 9/9C$ 421
Fri 25/97:35 p.m. -
1 stop7h 00m
Tue 6/101:20 p.m. -
1 stop8h 25m
Deal found 8/9C$ 434
Sat 10/107:35 p.m. -
1 stop8h 30m
Tue 13/106:45 a.m. -
2 stops15h 00m
Deal found 7/9C$ 436
Fri 25/97:35 p.m. -
1 stop7h 00m
Sat 3/101:20 p.m. -
1 stop8h 25m
Deal found 8/9C$ 436
Tue 6/107:35 p.m. -
1 stop8h 30m
Tue 13/106:45 a.m. -
2 stops15h 00m
Deal found 8/9C$ 437
Mon 28/97:35 p.m. -
1 stop7h 00m
Fri 2/101:20 p.m. -
1 stop8h 25m
Deal found 6/9C$ 440
Sat 26/910:30 a.m. -
2 stops10h 50m
Wed 7/101:20 p.m. -
1 stop8h 25m
Deal found 8/9C$ 441
Sat 10/107:35 p.m. -
1 stop8h 30m
Sat 17/106:45 a.m. -
2 stops15h 00m
Deal found 10/9C$ 447
Tue 29/97:35 p.m. -
1 stop8h 30m
Tue 6/106:45 a.m. -
2 stops15h 00m
Deal found 9/9C$ 448
Fri 25/97:35 p.m. -
1 stop7h 00m
Thu 1/101:20 p.m. -
1 stop8h 25m
Deal found 6/9C$ 455

Find flight deals from Seattle to Ontario

Round-trip from

C$ 398

One-way from

C$ 167

Popular in

July

Cheapest in

January

Average price

C$ 800

Good round-trip deal

C$ 694 or less

Good one-way deal

C$ 384 or less
WestJet
  • WestJet
  • 3/10-6/10
  • 3 total stops
  • 21h 50m total
  • Seattle to Ontario
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WestJet
  • WestJet
  • 8/10-31/12
  • 1 total stop
  • 7h 00m total
  • Seattle to Ontario
Search Deals
Highest demand for flights based on searches. 22% potential increase in price (C$ 249 potential increase over avg. RT price).
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Cheapest flight prices on average. 5% potential price decrease (C$ 42 potential savings vs. average RT price).
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Average for round-trip flights in September 2026
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Price to beat on a round-trip flight from Seattle/Tacoma Intl to Ontario.
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Price to beat on a one-way flight from Seattle/Tacoma Intl to Ontario.
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Cheapflights Fare Finder

 
Use the filters below to find and compare flights from Seattle to Ontario that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest round-trip

SeattleMontreal

SEA Seattle/Tacoma Intl - YUL Montreal Pierre Elliott Trudeau Intl

SEAYUL

Seattle/Tacoma Intl

Sun 11/10

7:35 p.m.-7:05 a.m.

1 stop8h 30m

Montreal Pierre Elliott Trudeau Intl

Wed 31/12

12:00 a.m.-9:00 p.m.

Nonstop0h 00m

C$ 189

SeattleMontreal

SEA Seattle/Tacoma Intl - YUL Montreal Pierre Elliott Trudeau Intl

SEAYUL

Seattle/Tacoma Intl

Thu 22/10

10:30 a.m.-12:25 a.m.

2 stops10h 55m

Montreal Pierre Elliott Trudeau Intl

Wed 31/12

12:00 a.m.-9:00 p.m.

Nonstop0h 00m

C$ 204

SeattleMontreal

SEA Seattle/Tacoma Intl - YUL Montreal Pierre Elliott Trudeau Intl

SEAYUL

Seattle/Tacoma Intl

Tue 6/10

7:35 p.m.-7:05 a.m.

1 stop8h 30m

Montreal Pierre Elliott Trudeau Intl

Wed 31/12

12:00 a.m.-9:00 p.m.

Nonstop0h 00m

C$ 214

SeattleMontreal

SEA Seattle/Tacoma Intl - YUL Montreal Pierre Elliott Trudeau Intl

SEAYUL

Seattle/Tacoma Intl

Fri 25/9

7:35 p.m.-7:05 a.m.

1 stop8h 30m

Montreal Pierre Elliott Trudeau Intl

Wed 31/12

12:00 a.m.-9:00 p.m.

Nonstop0h 00m

C$ 215

SeattleToronto

SEA Seattle/Tacoma Intl - YYZ Toronto Pearson Intl

SEAYYZ

Seattle/Tacoma Intl

Wed 21/10

8:36 p.m.-7:35 p.m.

3 stops19h 59m

Toronto Pearson Intl

Wed 31/12

12:00 a.m.-9:00 p.m.

Nonstop0h 00m

C$ 248

SeattleToronto

SEA Seattle/Tacoma Intl - YKF Toronto Region of Waterloo Intl

SEAYKF

Seattle/Tacoma Intl

Sat 17/10

7:35 p.m.-7:50 p.m.

1 stop21h 15m

Toronto Region of Waterloo Intl

Wed 31/12

12:00 a.m.-9:00 p.m.

Nonstop0h 00m

C$ 248

SeattleMontreal

SEA Seattle/Tacoma Intl - YUL Montreal Pierre Elliott Trudeau Intl

SEAYUL

Seattle/Tacoma Intl

Sat 24/10

5:50 a.m.-4:59 p.m.

1 stop8h 09m

Montreal Pierre Elliott Trudeau Intl

Wed 31/12

12:00 a.m.-9:00 p.m.

Nonstop0h 00m

C$ 250

SeattleToronto

SEA Seattle/Tacoma Intl - YKF Toronto Region of Waterloo Intl

SEAYKF

Seattle/Tacoma Intl

Sun 8/11

5:58 p.m.-3:45 p.m.

1 stop18h 47m

Toronto Region of Waterloo Intl

Wed 31/12

12:00 a.m.-9:00 p.m.

Nonstop0h 00m

C$ 251

SeattleToronto

SEA Seattle/Tacoma Intl - YKF Toronto Region of Waterloo Intl

SEAYKF

Seattle/Tacoma Intl

Tue 29/9

7:35 p.m.-7:50 p.m.

1 stop21h 15m

Toronto Region of Waterloo Intl

Wed 31/12

12:00 a.m.-9:00 p.m.

Nonstop0h 00m

C$ 254

SeattleOttawa

SEA Seattle/Tacoma Intl - YOW Ottawa

SEAYOW

Seattle/Tacoma Intl

Tue 8/12

7:45 a.m.-6:45 p.m.

1 stop8h 00m

Ottawa

Wed 31/12

12:00 a.m.-9:00 p.m.

Nonstop0h 00m

C$ 256

Flights are sorted by cheapest round-trip flights first.

Deals found on 5/9

Showing 1-10 of 60 resultsSorted by cheapest first
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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

Cheapflights Insights

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

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

Currently, January is the cheapest month in which you can book a flight from Seattle to Region of Ontario (average of C$ 378). Flying from Seattle to Region of Ontario in July is currently the most expensive (average of C$ 836). 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 ON?

When flying from Seattle to Region of Ontario, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.

Weekly flight availability from Seattle to Region of Ontario

The most flights from SEA to CAON are scheduled on a Monday (5 on average). You will have fewer flight options on Thursday, which is when the least amount of flights are scheduled (1 on average).

How much does it cost to fly round-trip from Seattle to Region of Ontario?

Airfare is below average for this route at the moment.
Seattle to Region of Ontario flights typically cost between C$ 586 and C$ 951 in October.
The cheapest round-trip price found within the last 5 days was C$ 481 on Multiple Airlines (22 Oct-2 Nov).

How far ahead should I book a flight from Seattle to Region of Ontario?

The price you pay for your flight from Seattle to Region of Ontario may vary depending on when you book. For the best chance of a lower fare, look to book 59 days in advance of your trip. Fares are likely to increase a fortnight or so before your departure date.

Reviews of airlines servicing Ontario

Check out reviews from past customers who have flown with Alaska Airlines,WestJet, andAir Canada from Seattle to Ontario to help guide your decision. Users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
7.9
Good
12,906 reviews
Check prices

Food

7.0

Boarding

8.1

Comfort

7.8

Entertainment

7.0

Crew

8.5

Overall

7.9

Reviews

1 / 20
6.0
Good

Anonymous,Jul 2026

SEA - LHR

Alaska has a brilliant crew. And the seats are good. As much as i loved my trip from Heathrow to Seattle, i definitely did not feel the same on the return flight. A lot was due to feeling very cramped and unfortunately for me, i had a kicker behind me and a passenger who did not stop moving (but constantly) next to me. The good was not good and i noticed that most people around me left most of their meal. The ice cream was very nice. I did not have breakfast. However the food was very nice on the way to Seattle
Alaska Airlines
7.9
Good
12,906 reviews
Alaska Airlines
7.9
Good
12,906 reviews
Check prices

Food

7.0

Boarding

8.1

Comfort

7.8

Entertainment

7.0

Crew

8.5

Overall

7.9

Reviews

1 / 20
6.0
Good

Anonymous,Jul 2026

SEA - LHR

Alaska has a brilliant crew. And the seats are good. As much as i loved my trip from Heathrow to Seattle, i definitely did not feel the same on the return flight. A lot was due to feeling very cramped and unfortunately for me, i had a kicker behind me and a passenger who did not stop moving (but constantly) next to me. The good was not good and i noticed that most people around me left most of their meal. The ice cream was very nice. I did not have breakfast. However the food was very nice on the way to Seattle
WestJet
7.2
Good
3,445 reviews
Alaska Airlines
7.9
Good
12,906 reviews
Check prices

Food

7.0

Boarding

8.1

Comfort

7.8

Entertainment

7.0

Crew

8.5

Overall

7.9

Reviews

1 / 20
6.0
Good

Anonymous,Jul 2026

SEA - LHR

Alaska has a brilliant crew. And the seats are good. As much as i loved my trip from Heathrow to Seattle, i definitely did not feel the same on the return flight. A lot was due to feeling very cramped and unfortunately for me, i had a kicker behind me and a passenger who did not stop moving (but constantly) next to me. The good was not good and i noticed that most people around me left most of their meal. The ice cream was very nice. I did not have breakfast. However the food was very nice on the way to Seattle
Air Canada
7.1
Good
11,608 reviews
Alaska Airlines
7.9
Good
12,906 reviews
Check prices

Food

7.0

Boarding

8.1

Comfort

7.8

Entertainment

7.0

Crew

8.5

Overall

7.9

Reviews

1 / 20
6.0
Good

Anonymous,Jul 2026

SEA - LHR

Alaska has a brilliant crew. And the seats are good. As much as i loved my trip from Heathrow to Seattle, i definitely did not feel the same on the return flight. A lot was due to feeling very cramped and unfortunately for me, i had a kicker behind me and a passenger who did not stop moving (but constantly) next to me. The good was not good and i noticed that most people around me left most of their meal. The ice cream was very nice. I did not have breakfast. However the food was very nice on the way to Seattle

Related info for your journey

  • What airport do you fly from for flights from Seattle to Ontario?

    Located just 18.4 km from the city centre, Seattle/Tacoma Intl (SEA) is the airport most travellers will use when flying to Ontario from Seattle.

  • How long is the flight from Seattle to Region of Ontario?

    There are many flights that can get you from Seattle to Region of Ontario in 8h 47m. Fly via WestJet, United Airlines, or Delta to get the fastest option. Airlines will cover a distance of 3663 km. Both multi-stop and direct flights can be found to your destination and back.

  • What are the cheapest airlines to fly from Seattle to Region of Ontario one-way?

    The cheapest airlines for a one-way flight from Seattle to Region of Ontario are Alaska Airlines (C$ 113), Air Canada (C$ 137), and WestJet (C$ 143).

  • What are the most popular routes from Seattle to Region of Ontario?

    When deciding which route to take from Seattle to Region of Ontario consider Seattle/Tacoma Intl - Toronto Pearson Intl, Seattle/Tacoma Intl - Toronto Island or Seattle/Tacoma Intl - Montreal Pierre Elliott Trudeau Intl as they are the most popular.

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

    Consider Qatar Airways (95%), Alaska Airlines (95%) or Air Canada (89%) when booking your flight. These represent the most reliable airlines when flying from Seattle to Region of Ontario.

  • What are the cheapest flights from Seattle to Region of Ontario?

    The cheapest flight price from Seattle to Region of Ontario is C$ 224. On average you can expect to pay C$ 751. The most popular route, (Seattle/Tacoma Intl - Toronto Pearson Intl), can usually be booked for C$ 470.

  • 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 Region of Ontario?

    Currently, January is the cheapest month in which you can book a flight from Seattle to Region of Ontario (average of C$ 378). Flying from Seattle to Region of Ontario in July is currently the most expensive (average of C$ 836). 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

Browse thousands of different options on Cheapflights for your next trip

Top 3 airlines flying from Seattle to Ontario

AirlineCheapestAverageFlexibilityOn-time
Alaska AirlinesCheapestC$ 281AverageC$ 770FlexibilityNo cancel feeOn-time75%
Search Alaska Airlines flights
WestJetCheapestC$ 285AverageC$ 522FlexibilityNo cancel feeOn-time60%
Search WestJet flights
Air CanadaCheapestC$ 364AverageC$ 744FlexibilityNo cancel feeOn-time67%
Search Air Canada flights

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