HomeSearch by dateVacation packagesHotelsFlight dealsCar rentalTravel tips & news
Seattle

$63+ Cheap flights from Ontario to Seattle (ONT - SEA)

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 5/25. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — SEA
Mar 2 — Mar 91
Sun 3/2
Sun 3/9
1 adult, Economy
We work with more than 300 partners to bring you better travel deals

Find cheap flights from Ontario to Seattle with Cheapflights

1. Tell us where you want to go
Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”
2. Select your favorite providers
We find the providers serving your travel needs. Choose up to four travel providers to compare side-by-side for flights, hotels, or car rentals.
3. Compare prices and book
Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.

The best prices from Ontario to Seattle/Tacoma Intl are usually found in October or January, booked 78 days in advance, depart on a Friday or Thursday and return on a Thursday

Cheap flight deals from Ontario to Seattle

Discover tips and strategies to find the most affordable flight options for your journey from Ontario (ONT) to Seattle (SEA). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated February 25, 2025.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$97
(Kiwi.com)

One-way from

$63
(Kiwi.com)

Popular in

December

Cheapest in

October

Average price

$201

Good round-trip deal

$166 or less

Good one-way deal

$114 or less
Provider with most accurate pricing for Ontario-Seattle/Tacoma Intl flight deals.
Search Deals
Provider most trusted by Cheapflights users for Ontario-Seattle/Tacoma Intl flights.
Search Deals
From Ontario to Seattle/Tacoma Intl
Search Deals
One-way flight from Ontario to Seattle/Tacoma Intl
Search Deals
Highest demand for flights based on searches. 2% potential increase in price ($3 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease ($6 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in February 2025
Search Deals
Price to beat on a round-trip flight from Ontario to Seattle/Tacoma Intl.
Search Deals
Price to beat on a one-way flight from Ontario to Seattle/Tacoma Intl.
Search Deals

Find flight deals from Ontario to Seattle

Cheapest flights from Ontario to Seattle
Explore the most affordable flight options available from Ontario to Seattle. Find the lowest fares from popular airlines and budget airlines, with prices last updated on February 25, 2025.

This Kiwi.com deal was found by Cheapflights users on 2/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 5/44:29 pmONT - SEA
Nonstop3h 03mFrontier
Mon 5/56:50 pmSEA - ONT
Nonstop2h 35mFrontier
Deal found 2/24$97
This Southwest deal was found by Cheapflights users on 2/25. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/610:35 amONT - SEA
1 stop5h 50mSouthwest
Wed 5/75:10 pmSEA - ONT
1 stop4h 35mSouthwest
Deal found 2/25$153
This Expedia deal was found by Cheapflights users on 2/25. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 3/186:00 amONT - SEA
Nonstop2h 50mMultiple Airlines
Fri 3/2112:52 pmSEA - ONT
Nonstop2h 37mMultiple Airlines
Deal found 2/25$173
This Delta deal was found by Cheapflights users on 2/25. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/65:45 amONT - SEA
Nonstop2h 55mDelta
Wed 5/73:35 pmSEA - ONT
Nonstop2h 44mDelta
Deal found 2/25$177
This United Airlines deal was found by Cheapflights users on 2/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 4/296:00 amONT - SEA
1 stop5h 49mUnited Airlines
Sat 5/35:00 amSEA - ONT
1 stop7h 24mUnited Airlines
Deal found 2/24$182
This Trip.com deal was found by Cheapflights users on 2/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 3/186:00 amONT - SEA
Nonstop2h 50mHawaiian Airlines
Sat 3/229:23 pmSEA - ONT
Nonstop2h 36mHawaiian Airlines
Deal found 2/24$186
This Alaska Airlines deal was found by Cheapflights users on 2/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 3/196:00 amONT - SEA
Nonstop2h 50mAlaska Airlines
Sat 3/229:23 pmSEA - ONT
Nonstop2h 36mAlaska Airlines
Deal found 2/24$187

Find flights from Ontario to Seattle within your budget

Customize your flight search to find flights from Ontario to Seattle that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated February 25, 2025.

Fly from

Ontario

Fly to

Seattle

Route

Depart

Return

Price

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Sun 5/4

4:29 pm-7:32 pm

Nonstop3h 03m

Seattle/Tacoma Intl

Mon 5/5

6:50 pm-9:25 pm

Nonstop2h 35m

$97

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Tue 5/6

10:35 am-4:25 pm

1 stop5h 50m

Seattle/Tacoma Intl

Wed 5/7

5:10 pm-9:45 pm

1 stop4h 35m

$153

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Tue 3/18

6:00 am-8:50 am

Nonstop2h 50m

Seattle/Tacoma Intl

Fri 3/21

12:52 pm-3:29 pm

Nonstop2h 37m

$173

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Tue 5/6

5:45 am-8:40 am

Nonstop2h 55m

Seattle/Tacoma Intl

Wed 5/7

3:35 pm-6:19 pm

Nonstop2h 44m

$177

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Tue 4/29

6:00 am-11:49 am

1 stop5h 49m

Seattle/Tacoma Intl

Sat 5/3

5:00 am-12:24 pm

1 stop7h 24m

$182

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Tue 3/18

6:00 am-8:50 am

Nonstop2h 50m

Seattle/Tacoma Intl

Sat 3/22

9:23 pm-11:59 pm

Nonstop2h 36m

$186

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Wed 3/19

6:00 am-8:50 am

Nonstop2h 50m

Seattle/Tacoma Intl

Sat 3/22

9:23 pm-11:59 pm

Nonstop2h 36m

$187

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Sun 5/25

1:19 pm-4:08 pm

Nonstop2h 49m

$63

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Tue 3/25

6:55 pm-10:55 pm

1 stop4h 00m

$77

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Wed 3/26

5:40 am-8:37 am

Nonstop2h 57m

$89

Flights are sorted by cheapest round-trip flights first.

Deals found on 2/24

Showing 1-10 of 15 results
1
2

Compare providers for flights from Ontario to Seattle

Provider information is updated monthly. Please note that these providers often have deals for this flight, but the availability may vary on a day-by-day basis on Cheapflights.
Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from Ontario to Seattle in February.
ProviderPrice AccuracyTrust Score*
ExpediaPrice Accuracy1 starTrust Score*3 stars
FlightHubPrice Accuracy3 starsTrust Score*3 stars
eDreamsPrice Accuracy3 starsTrust Score*3 stars
CheapflightsfaresPrice Accuracy3 starsTrust Score*2 stars
Kiwi.comPrice Accuracy3 starsTrust Score*2 stars
CheapfaremartPrice Accuracy-Trust Score*3 stars
CheapOairPrice Accuracy1 starTrust Score*3 stars
PricelinePrice Accuracy1 starTrust Score*3 stars
Justfly.comPrice Accuracy3 starsTrust Score*3 stars
MytripPrice Accuracy3 starsTrust Score*3 stars

*The Trust Score is based on feedback from users after their booking experience. It measures overall satisfaction, helping us identify issues like hidden fees, problems during the ticketing process, and the quality of customer service. This score is our best indicator of the provider's quality and reliability.

  • Most accurate provider: When it comes to deals on Ontario-Seattle flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on Ontario-Seattle flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from Ontario-Seattle flight searches over the past month and is updated monthly.
  • Most trusted provider: When it comes to deals on Ontario-Seattle flights, Cheapflights users trust FlightHub the most. FlightHub has received a user feedback score of 3 out of 3 stars (3 being the best), meaning they have been trusted the most by Cheapflights users looking for Ontario-Seattle flight deals. Provider user feedback score is based on Cheapflights searches over the past month and is updated monthly.

Best time to book a flight from Ontario to Seattle

Have a flexible travel schedule? Discover the best time to fly to Seattle from Ontario with our price prediction graph.
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Travel insights for flights from Ontario to Seattle

Get recent, data-driven insights about flights from Ontario to Seattle including ideal travel times, pricing trends, and more.

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

Use this chart to determine the optimal time to book a round-trip flight from Ontario to Seattle. Price data was last updated on February 14, 2025.

To ensure you get the cheapest price possible for a flight from Ontario to Seattle, you should look to book at least 78 days in advance of your intended travel date. The price of your flight may increase if you delay and leave booking until a week or so before departure.

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

Currently, January is the cheapest month in which you can book a flight from Ontario to Seattle (average of $238). Flying from Ontario to Seattle in July is currently the most expensive (average of $411). 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 ONT to SEA?

Find hourly flight availability from Ontario to Seattle. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated February 25, 2025.

It’s typically best to fly out from Ontario to Seattle in the morning. Doing so could potentially save you 42% on the flight price compared to flying at noon, which is usually more expensive.

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

Use this chart to determine the cheapest time to fly round-trip from Ontario to Seattle. Price data was last updated on February 23, 2025.

Travelers seeking maximum savings on their Ontario to Seattle flight should consider departing on Friday mornings when fares are most often at their lowest. Sunday at noon flights should be avoided if possible as fares are typically the most expensive at this time.

Weekly flight availability from Ontario to Seattle

Explore weekly flight availability from Ontario to Seattle. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated February 25, 2025.

The most flights from ONT to SEA are scheduled on a Monday (14 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (5 on average).

Rainfall in Seattle by month

Plan your trip to Seattle by taking into account the average rainfall totals by month.

In terms of precipitation, rainfall in Seattle ranges from 0.7 - 6.6 inches per month. November is typically the wettest month, when rainfall can reach 6.6 in. July is typically the driest time to visit Seattle when rainfall is around 0.7 in.

Temperature in Seattle by month

Plan your trip to Seattle by taking into account the average temperature totals by month.

If weather is an important factor for your trip to Seattle, use this chart to help with planning. For those seeking warmer temperatures, July is the ideal time of year to visit, when temperatures reach an average of 66.2 F. Travelers looking to avoid the cold should look outside of December, when temperatures are typically at their lowest (around 41.0 F).

Reviews of airlines servicing Seattle

Get insights into the airlines that provide service to Seattle. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Seattle. Reviews last updated February 25, 2025.
Read reviews from past customers who have flown Southwest, Alaska Airlines and Delta from Ontario to Seattle. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.1
Very good
4,374 reviews

Entertainment

7.6

Crew

8.7

Comfort

8.1

Overall

8.1

Food

7.1

Boarding

8.2

Reviews

1 / 20

10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.

Southwest
8.1
Very good
4,374 reviews
Southwest
8.1
Very good
4,374 reviews

Entertainment

7.6

Crew

8.7

Comfort

8.1

Overall

8.1

Food

7.1

Boarding

8.2

Reviews

1 / 20

10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.

Alaska Airlines
8.0
Very good
9,713 reviews
Southwest
8.1
Very good
4,374 reviews

Entertainment

7.6

Crew

8.7

Comfort

8.1

Overall

8.1

Food

7.1

Boarding

8.2

Reviews

1 / 20

10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.

Delta
8.0
Very good
8,163 reviews
Southwest
8.1
Very good
4,374 reviews

Entertainment

7.6

Crew

8.7

Comfort

8.1

Overall

8.1

Food

7.1

Boarding

8.2

Reviews

1 / 20

10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.

Hawaiian Airlines
7.9
Good
2,312 reviews
Southwest
8.1
Very good
4,374 reviews

Entertainment

7.6

Crew

8.7

Comfort

8.1

Overall

8.1

Food

7.1

Boarding

8.2

Reviews

1 / 20

10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.

United Airlines
7.4
Good
8,734 reviews
Southwest
8.1
Very good
4,374 reviews

Entertainment

7.6

Crew

8.7

Comfort

8.1

Overall

8.1

Food

7.1

Boarding

8.2

Reviews

1 / 20

10.0
Excellent

Merlyn,Feb 2025

LAX - SMF

New Terminal is neat, lost of stores and places to catch a bite.

Related info for your journey

Find useful and relevant information for your journey from Ontario to Seattle. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airports do I use to fly from Ontario to Seattle?

    If you wish to fly to Seattle from Ontario, then you need to book flights from Ontario to Seattle/Tacoma Intl. There are 9 flights from Ontario (ONT) to Seattle/Tacoma Intl (SEA) per day to choose from. Flights to Seattle from Ontario are available from 6 different airlines, which means you should have some options if you want to compare airfare deals. 2h 43m is how long a nonstop flight from Ontario to Seattle/Tacoma Intl typically takes.

  • How popular is this Ontario to Seattle flight route?

    The Ontario to Seattle/Tacoma Intl flight path was viewed by 169 users in the past month. Keep an eye out for changes in search interest prior to high and low season.

  • What are the cheapest airlines flying from Ontario to Seattle round-trip?

    Cheapflights users have booked flights from Ontario to Seattle round-trip from $97. Other airlines that can offer you cheap pricing are Southwest, from $153, and Delta, from $177. You may be able to fly from Ontario to Seattle for 48% less than the average price by searching for these airlines.

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

    The cheapest airlines for a one-way flight from Ontario to Seattle are Frontier ($63), Southwest ($77), and Delta ($89).

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

    Consider WestJet (98%), Frontier (95%) or SkyWest Airlines (92%) when booking your flight. These represent the most reliable airlines when flying from Ontario to Seattle.

  • What are the cheapest flights from Ontario to Seattle?

    While on average a flight from Ontario to Seattle is generally $694, our data shows the cheapest flight currently is $45. When looking at the most popular route, (Ontario - Seattle/Tacoma Intl), you can expect to pay $82 for that flight.

  • Can I find deals for flights from Ontario to Seattle that include hotel bookings?

    Yes. In addition to deals on Ontario to Seattle flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Ontario to Seattle?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Ontario to Seattle.

  • Can I find deals for business class flights from Ontario to Seattle?

    Yes. Cheapflights offers flight deals from Ontario to Seattle 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 Ontario to Seattle?

    Currently, January is the cheapest month in which you can book a flight from Ontario to Seattle (average of $238). Flying from Ontario to Seattle in July is currently the most expensive (average of $411). 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

Traveling to a place near Ontario?

Book flights to Ontario if you plan to visit one of these locations
SeaTac
Tukwila
Renton
Tacoma
Lacey
Ocean Shores
Leavenworth
Federal Way
Centralia
Olympia
Cle Elum
Lakewood
Mukilteo
Aberdeen
Issaquah
Shoreline
Lynnwood
Shelton
Silverdale
Redmond

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Alternative routes for Ontario to Seattle

See prices for flight routes from nearby airports that may be better suited for you.
Los Angeles to Seattle flights
San Francisco to Seattle flights
Los Angeles to Portland flights
San Diego to Seattle flights
Santa Ana to Seattle flights
Burbank to Seattle flights
San Jose to Seattle flights
Oakland to Seattle flights
Sacramento to Seattle flights
Burbank to Portland flights
Ontario to Portland flights
Santa Ana to Portland flights
San Francisco to Portland flights
Las Vegas to Seattle flights
Los Angeles to Everett flights
San Diego to Portland flights
San Francisco to Everett flights
San Jose to Portland flights
Oakland to Portland flights
San Diego to Everett flights
Los Angeles to Spokane flights
Fresno to Seattle flights
Santa Ana to Everett flights
Sacramento to Portland flights
San Luis Obispo to Seattle flights
Reno to Seattle flights
Palm Springs to Seattle flights
San Francisco to Spokane flights
Santa Rosa to Seattle flights
Long Beach to Seattle flights
Las Vegas to Portland flights
Palm Springs to Portland flights
Reno to Portland flights
Las Vegas to Everett flights
Ontario to Spokane flights
Monterey to Seattle flights
Santa Rosa to Portland flights
San Jose to Everett flights
Santa Barbara to Portland flights
Fresno to Portland flights
San Luis Obispo to Portland flights
San Diego to Spokane flights
Santa Barbara to Seattle flights
Medford to Seattle flights
Long Beach to Portland flights
Redding to Seattle flights
Los Angeles to Pasco flights
Sacramento to Spokane flights
Fresno to Spokane flights

Top 6 airlines flying from Ontario to Seattle

Discover the top 6 airlines that operate flights from Ontario to Seattle. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated February 25, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$61Average$139FlexibilityNo cancel feeOn-time62%
Spirit AirlinesCheapest$71Average$130FlexibilityNo cancel feeOn-time65%
Hawaiian AirlinesCheapest$82Average$242FlexibilityNo cancel feeOn-time85%
DeltaCheapest$107Average$250FlexibilityNo cancel feeOn-timeN/A
Alaska AirlinesCheapest$135Average$258FlexibilityNo cancel feeOn-time75%
SouthwestCheapest$186Average$297FlexibilityNo cancel feeOn-time63%
100% Free
Cheapflights is completely free to use, so you can start saving the moment you arrive.
Book with Flexibility
Our users can plan ahead with confidence and find flights with no change fees
Travel Smart
Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.