What day of the week experiences the fewest flight delays on this route?

Sunday is statistically the day of the week which experiences the fewest number of delays on this flight route. Friday has historically seen more delays on average compared to the rest of the week.

How many flights depart from Ontario to Seattle on average per day?

The number of flights available between Ontario and Seattle is 16 per day as of November 2025. The most frequent departure time is 6:00AM, with 78% of daily flights leaving at noon.

What is the most punctual flight time for Ontario to Seattle flights?

Generally, flights departing in the morning tend to experience fewer delays. Flights in the evening have, in the past, seen delays more frequently in comparison.

How many flights depart from Ontario to Seattle on average per week?

As of November 2025, there are 113 flights per week flying from Ontario to Seattle. The most common day of the week flights depart is Wed, with 21% of flights taking off on this day.

Which airline has the best punctuality record on Ontario to Seattle flights?

According to our data, Delta have had the least number of delays on this route over the last 12 months; with about 4% of their flights experiencing any sort of delay.

What airlines fly to Seattle?

Alaska Airlines, Frontier and Delta are the top three most popular airlines that fly to Seattle from Ontario according to our data. Alaska Airlines is the first choice among our users, with 45% of people opting to fly with this airline when traveling to Seattle. Keep in mind that there are 8 different airlines that fly to Seattle on a routine basis, so you have a few additional options to choose from.

What is the cheapest airline that flies from Ontario to Seattle/Tacoma Intl?

Southwest, Alaska Airlines, and Delta are the most popular carriers operating from Ontario to Seattle/Tacoma Intl

How often are flights from Ontario to Seattle delayed?

Historically, on average around 8% of flights between Ontario and Seattle have experienced a delay on any given week. The average delay length over the past 12 months has been 133 minutes.

When did momondo last update prices for flights from Ontario Airport to Seattle/Tacoma Intl Airport?

Prices for flights from Ontario Airport to Seattle/Tacoma Intl Airport are updated daily.

How many operators does momondo search for flights from Ontario Airport to Seattle/Tacoma Intl Airport?

The number of operators available for flights from Ontario Airport to Seattle/Tacoma Intl Airport is 5 as of November 2025.

How old do you have to be to fly from Ontario Airport to Seattle/Tacoma Intl Airport?

The minimum age a child must be to fly alone is five but airlines that offer an unaccompanied minor (UNMR) service will have their own age restrictions, including rules around flight length, timings, and stopovers. We always recommend checking with the individual airline you are booking with to travel from Ontario Airport to Seattle/Tacoma Intl Airport.

What documentation or ID do you need to fly to Seattle/Tacoma Intl Airport?

The necessary travel and health documents for your Seattle/Tacoma Intl Airport trip may vary depending on your travel plans and individual circumstances. Generally, you should have various documents, such as a national ID card or driver's license and a passport that is valid for six months beyond your scheduled arrival date. We recommend seeking advice from your airline or a trusted third party, such as IATA.

$76 Cheap Flights from Ontario to Seattle in 2025/26

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Cheap round-trip flights

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6:00 am - 8:57 amONT-SEA

2h 57mnonstop

11:06 am - 1:42 pmSEA-ONT

2h 36mnonstop

$126Multiple Airlines

Find Deal

Tue, Dec 16 - Fri, Jan 2

6:00 am - 12:57 pmONT-SEA

6h 57m1 stop

8:15 am - 11:02 amSEA-ONT

2h 47mnonstop

$129Delta

Find Deal

Tue, Dec 16 - Sun, Jan 4

6:45 am - 12:30 pmONT-SEA

29h 45m1 stop

11:06 am - 1:42 pmSEA-ONT

2h 36mnonstop

$130Frontier

Find Deal

Thu, Dec 18 - Fri, Jan 2

6:00 pm - 10:11 amONT-SEA

16h 11m1 stop

11:06 am - 1:42 pmSEA-ONT

2h 36mnonstop

$131Frontier

Find Deal

Mon, Dec 29 - Mon, Jan 5

2:45 pm - 5:38 pmONT-SEA

2h 53mnonstop

11:06 am - 1:42 pmSEA-ONT

2h 36mnonstop

$133Frontier

Find Deal

Tue, Dec 23 - Mon, Jan 5

7:10 am - 11:49 amONT-SEA

4h 39m1 stop

11:06 am - 1:42 pmSEA-ONT

2h 36mnonstop

$135Multiple Airlines

Find Deal

Tue, Dec 16 - Fri, Jan 2

4:36 pm - 7:27 pmONT-SEA

2h 51mnonstop

11:06 am - 1:42 pmSEA-ONT

2h 36mnonstop

$136Multiple Airlines

Find Deal

Thu, Dec 18 - Mon, Jan 5

6:00 am - 8:57 amONT-SEA

2h 57mnonstop

12:31 pm - 3:08 pmSEA-ONT

2h 37mnonstop

$137Alaska Airlines

Find Deal

Fri, Dec 19 - Mon, Jan 12

12:02 pm - 2:52 pmONT-SEA

2h 50mnonstop

8:56 pm - 11:32 pmSEA-ONT

2h 36mnonstop

$138Alaska Airlines

Find Deal

Sat, Feb 14 - Fri, Feb 20

6:00 am - 12:33 pmONT-SEA

6h 33m1 stop

5:30 am - 12:16 pmSEA-ONT

6h 46m1 stop

$139Delta

Find Deal

Sat, Jan 24 - Tue, Jan 27

Delta flights from Ontario to Seattle

Our best Delta deals on Ontario to Seattle flight tickets

Delta

Dec 16

ONT6:00 amOntario

6h 57m

1 stop

SEA12:57 pmSeattle/Tacoma Intl

Jan 4

SEA8:15 amSeattle/Tacoma Intl

2h 47m

ONT11:02 amOntario

$129

Find similar

Delta

Jan 24

ONT6:00 amOntario

6h 33m

1 stop

SEA12:33 pmSeattle/Tacoma Intl

Jan 27

SEA5:30 amSeattle/Tacoma Intl

6h 46m

1 stop

ONT12:16 pmOntario

$139

Find similar

Delta

Dec 10

ONT5:49 pmOntario

3h 00m

SEA8:49 pmSeattle/Tacoma Intl

Dec 16

SEA8:30 amSeattle/Tacoma Intl

2h 43m

ONT11:13 amOntario

$248

Find similar

Alaska Airlines flights from Ontario to Seattle

Our best Alaska Airlines deals on Ontario to Seattle flight tickets

Alaska Airlines

Dec 19

ONT6:00 amOntario

2h 57m

SEA8:57 amSeattle/Tacoma Intl

Jan 12

SEA12:31 pmSeattle/Tacoma Intl

2h 37m

ONT3:08 pmOntario

$137

Find similar

Alaska Airlines

Feb 14

ONT12:02 pmOntario

2h 50m

SEA2:52 pmSeattle/Tacoma Intl

Feb 20

SEA8:56 pmSeattle/Tacoma Intl

2h 36m

ONT11:32 pmOntario

$138

Find similar

Alaska Airlines

Dec 17

ONT7:10 amOntario

4h 39m

1 stop

SEA11:49 amSeattle/Tacoma Intl

Jan 5

SEA9:35 pmSeattle/Tacoma Intl

2h 39m

ONT12:14 amOntario

$148

Find similar

Fly from

Fly to

Route

Depart

Return

Price

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Tue 12/16

6:00 am-8:57 am

Nonstop2h 57m

Seattle/Tacoma Intl

Fri 1/2

11:06 am-1:42 pm

Nonstop2h 36m

$126

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Tue 12/16

6:00 am-12:57 pm

1 stop6h 57m

Seattle/Tacoma Intl

Sun 1/4

8:15 am-11:02 am

Nonstop2h 47m

$129

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Thu 12/18

6:45 am-12:30 pm

1 stop29h 45m

Seattle/Tacoma Intl

Fri 1/2

11:06 am-1:42 pm

Nonstop2h 36m

$130

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Mon 12/29

6:00 pm-10:11 am

1 stop16h 11m

Seattle/Tacoma Intl

Mon 1/5

11:06 am-1:42 pm

Nonstop2h 36m

$131

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Tue 12/23

2:45 pm-5:38 pm

Nonstop2h 53m

Seattle/Tacoma Intl

Mon 1/5

11:06 am-1:42 pm

Nonstop2h 36m

$133

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Tue 12/16

7:10 am-11:49 am

1 stop4h 39m

Seattle/Tacoma Intl

Fri 1/2

11:06 am-1:42 pm

Nonstop2h 36m

$135

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Thu 12/18

4:36 pm-7:27 pm

Nonstop2h 51m

Seattle/Tacoma Intl

Mon 1/5

11:06 am-1:42 pm

Nonstop2h 36m

$136

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Fri 12/19

6:00 am-8:57 am

Nonstop2h 57m

Seattle/Tacoma Intl

Mon 1/12

12:31 pm-3:08 pm

Nonstop2h 37m

$137

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Sat 2/14

12:02 pm-2:52 pm

Nonstop2h 50m

Seattle/Tacoma Intl

Fri 2/20

8:56 pm-11:32 pm

Nonstop2h 36m

$138

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Sat 1/24

6:00 am-12:33 pm

1 stop6h 33m

Seattle/Tacoma Intl

Tue 1/27

5:30 am-12:16 pm

1 stop6h 46m

$139

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 20 resultsSorted by cheapest first

How to get the cheapest flight ticket from Ontario to Seattle

Look no further. We've gone through all the searches for this route on momondo so you have the important information and insights to find the cheapest flight ticket for your trip

Prices

Airlines

Delays

Other information

What is the typical price of a round-trip flight between Ontario and Seattle?

What is the cheapest month to fly to Seattle?

In general, January is the cheapest month to fly from Ontario to Seattle. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $157. If you don’t want to visit Seattle in January, then you should wait until February to fly from Ontario, when ticket prices are also cheap, with an average price of $177.

What is the cheapest day to depart on your flight to Seattle?

On average, the least expensive day to fly to Seattle from Ontario is on a Friday. momondo users have found tickets for Friday departures for as low as $271. However, this price may fluctuate depending on the airline, the season, and holidays. On the other hand, Sunday is the most expensive day to depart from Ontario because it is more convenient for both business and leisure travelers. As a result, prices tend to be around $358.

What is the cheapest time of day to depart on your flight to Seattle?

Flying to Seattle from Ontario in the afternoon is the least expensive time of day to depart. momondo users have found prices as low as $238 when looking at flights departing in the afternoon. Flights to Seattle are more costly in the morning, with an average ticket price of $330. Departure times in the morning fall within the peak daily travel times, which is why tickets can be more expensive.

What is the cheapest Ontario to Seattle/Tacoma Intl flight route?

Fly from Ontario to Seattle/Tacoma Intl for the best Ontario - Seattle/Tacoma Intl flight prices

How far in advance should I book a flight to Seattle?

You are more likely to see cheaper flights to Seattle from Ontario when booking weeks ahead of your departure date. In general, you can expect to find flights to Seattle for around $210 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Seattle from Ontario for as low as $173 on momondo.

What cabin class options are available on Ontario to Seattle/Tacoma Intl flights?

There are 4 cabin classes available to choose from on Ontario to Seattle/Tacoma Intl flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Can stopping save me money on Ontario to Seattle flights?

No. A direct flight is the cheapest option for a flight between Ontario to Seattle.

How have Ontario to Seattle flight prices changed over time?

As of November 2025, prices for Ontario to Seattle flights are approximately 3% more expensive when compared to flights at the same time last year.

When to book flights from Ontario to Seattle

Are you open to changing your travel dates? Check out the ideal times to fly from Ontario to Seattle according to our flight data. Find out which month and days have the cheapest flights.

Estimated round-trip price

Cheap Ontario to Seattle (ONT to SEA) flight deals and tips

Find info about flight duration, direct flights, and airports for your flight from Ontario to Seattle

Best Price Found	$128
Fastest flight time	2h 49m
Direct flights	Every day
Airports in Seattle	1 airport

The best one-way flight to Seattle from Ontario in the past 72 hours is $128. The best round-trip flight deal from Ontario to Seattle found on momondo in the last 72 hours is $176.

The fastest flight from Ontario to Seattle takes 2h 49m

Direct flights go from Ontario to Seattle every day.

There is 1 airport near Seattle: Seattle/Tacoma Intl (SEA)

Search flight deals

How far is Ontario to Seattle/Tacoma Intl by plane?
The straight-line distance from Ontario to Seattle/Tacoma Intl is 966.6 mi. By plane, this route typically takes 2h 50m.
When did momondo last update prices for flights from Ontario Airport to Seattle/Tacoma Intl Airport?
Prices for flights from Ontario Airport to Seattle/Tacoma Intl Airport are updated daily.
How many operators does momondo search for flights from Ontario Airport to Seattle/Tacoma Intl Airport?
The number of operators available for flights from Ontario Airport to Seattle/Tacoma Intl Airport is 5 as of November 2025.
How old do you have to be to fly from Ontario Airport to Seattle/Tacoma Intl Airport?
The minimum age a child must be to fly alone is five but airlines that offer an unaccompanied minor (UNMR) service will have their own age restrictions, including rules around flight length, timings, and stopovers. We always recommend checking with the individual airline you are booking with to travel from Ontario Airport to Seattle/Tacoma Intl Airport.
What documentation or ID do you need to fly to Seattle/Tacoma Intl Airport?
The necessary travel and health documents for your Seattle/Tacoma Intl Airport trip may vary depending on your travel plans and individual circumstances. Generally, you should have various documents, such as a national ID card or driver's license and a passport that is valid for six months beyond your scheduled arrival date. We recommend seeking advice from your airline or a trusted third party, such as IATA.
What is the most popular plane model from Ontario to Seattle?
Based on momondo bookings for this flight route, the most popular plane model on flight routes from Ontario to Seattle is Boeing 737-800 Passenger/BBJ2 (winglets) (18.79% of total bookings). The next most popular plane models are Boeing 737-900 Passenger/BBJ3 (winglets) (14.48%), Airbus A320neo (11.35%), and Boeing 737-700 (10.98%).
What is the most popular airline from Ontario to Seattle?
Based on momondo bookings for this flight route, the most popular airline on flight routes from Ontario to Seattle is Frontier (41% of total bookings). The next most popular airlines are Alaska Airlines (32%), Delta (19%), and Hawaiian Airlines (7%).

Best airlines flying from Ontario to Seattle

Compare and see reviews for airlines that fly from Ontario to Seattle with momondo

Airline	Rating	Free Cancellation	Price
Frontier	PriceFrom $84	Free Cancellation	Rating 5.8 3,099 reviews	Search Frontier flights
Hawaiian Airlines	PriceFrom $98	Free Cancellation	Rating 7.8 2,814 reviews	Search Hawaiian Airlines flights
Delta	PriceFrom $119	Free Cancellation	Rating 7.9 7,998 reviews	Search Delta flights
Alaska Airlines	PriceFrom $147	Free Cancellation	Rating 8.0 11,354 reviews	Search Alaska Airlines flights
Southwest	PriceFrom $150	Free Cancellation	Rating 8.0 4,254 reviews	Search Southwest flights

Alaska Airlines Flights From Ontario to Seattle
Alaska Airlines flight deals from Ontario to Seattle start from $147 round-trip. Over the 13 Alaska Airlines flights for this route in a normal week, average airfare is usually $268 round-trip - but some users have found much cheaper deals with momondo.
Delta Flights From Ontario to Seattle
$119 is the best Delta flight deal from Ontario to Seattle found on momondo over the last 72 hours. The average Delta ticket price found was closer to $255, however, with flight time and availability significantly affecting the price. Delta (7.9/10 from 8,004 user reviews) flies into Seattle from Ontario 13 times in an average week so prices can vary.

Tacoma

Leavenworth

SeaTac

Ocean Shores

Renton

Olympia

Lynnwood

Kent

Marysville

Puyallup

Redmond

Tukwila

Cle Elum

Lakewood

Federal Way

Fife

Centralia

Kirkland

Westport

Shoreline

Why use momondo?

Why should I use momondo to find a flight deal from Ontario to Seattle?

momondo collates all your flight options in one place and lets you filter them to find the perfect flight from Ontario to Seattle. momondo saves you time and could save you money on your trip.

Can I find flights from Ontario to Seattle with flexible booking policies on momondo?

Yes. momondo enables you to select and highlight flights to Seattle from Ontario with this policy.

How can momondo help me find flights from Ontario to Seattle?

momondo helps you find the best flight between Ontario and Seattle by providing filters to narrow your choice of flights to those matching your criteria. You can select flights based on numerous factors such as price, departure and landing times, airport and airline.

I’m not ready to book a flight from Ontario to Seattle right now. Can momondo alert me if prices change?

Price alerts on flights to Seattle from Ontario are quick and easy to set up on momondo. Simply perform a search and select the price alert feature. It is as simple as that.

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Cheap flights from Ontario to Seattle from $76

This is the cheapest one-way flight price found by a momondo user in the last 72 hours by searching for a flight from Ontario to Seattle departing on 12/25. Fares may change, and may not be available for all flights or travel dates. Click the price to refresh the search for this deal.

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Our best Alaska Airlines deals on Ontario to Seattle flight tickets

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How to get the cheapest flight ticket from Ontario to Seattle

Look no further. We've gone through all the searches for this route on momondo so you have the important information and insights to find the cheapest flight ticket for your trip

What is the typical price of a round-trip flight between Ontario and Seattle?

What is the cheapest month to fly to Seattle?

What is the cheapest day to depart on your flight to Seattle?

What is the cheapest time of day to depart on your flight to Seattle?

What is the cheapest Ontario to Seattle/Tacoma Intl flight route?

Fly from Ontario to Seattle/Tacoma Intl for the best Ontario - Seattle/Tacoma Intl flight prices

How far in advance should I book a flight to Seattle?

What cabin class options are available on Ontario to Seattle/Tacoma Intl flights?

There are 4 cabin classes available to choose from on Ontario to Seattle/Tacoma Intl flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Can stopping save me money on Ontario to Seattle flights?

No. A direct flight is the cheapest option for a flight between Ontario to Seattle.

How have Ontario to Seattle flight prices changed over time?

As of November 2025, prices for Ontario to Seattle flights are approximately 3% more expensive when compared to flights at the same time last year.

What is the cheapest airline that flies from Ontario to Seattle/Tacoma Intl?

Southwest, Alaska Airlines, and Delta are the most popular carriers operating from Ontario to Seattle/Tacoma Intl

What airlines fly to Seattle?

How often are flights from Ontario to Seattle delayed?

Historically, on average around 8% of flights between Ontario and Seattle have experienced a delay on any given week. The average delay length over the past 12 months has been 133 minutes.

What is the most punctual flight time for Ontario to Seattle flights?

Generally, flights departing in the morning tend to experience fewer delays. Flights in the evening have, in the past, seen delays more frequently in comparison.

What day of the week experiences the fewest flight delays on this route?

Sunday is statistically the day of the week which experiences the fewest number of delays on this flight route. Friday has historically seen more delays on average compared to the rest of the week.

Which airline has the best punctuality record on Ontario to Seattle flights?

According to our data, Delta have had the least number of delays on this route over the last 12 months; with about 4% of their flights experiencing any sort of delay.

How many flights depart from Ontario to Seattle on average per day?

The number of flights available between Ontario and Seattle is 16 per day as of November 2025. The most frequent departure time is 6:00AM, with 78% of daily flights leaving at noon.

How many flights depart from Ontario to Seattle on average per week?

As of November 2025, there are 113 flights per week flying from Ontario to Seattle. The most common day of the week flights depart is Wed, with 21% of flights taking off on this day.

When to book flights from Ontario to Seattle

Cheap Ontario to Seattle (ONT to SEA) flight deals and tips

Find info about flight duration, direct flights, and airports for your flight from Ontario to Seattle

Best Price Found

Fastest flight time

Direct flights

Airports in Seattle

How far is Ontario to Seattle/Tacoma Intl by plane?

When did momondo last update prices for flights from Ontario Airport to Seattle/Tacoma Intl Airport?

How many operators does momondo search for flights from Ontario Airport to Seattle/Tacoma Intl Airport?

How old do you have to be to fly from Ontario Airport to Seattle/Tacoma Intl Airport?

What documentation or ID do you need to fly to Seattle/Tacoma Intl Airport?

What is the most popular plane model from Ontario to Seattle?

What is the most popular airline from Ontario to Seattle?

Best airlines flying from Ontario to Seattle

Compare and see reviews for airlines that fly from Ontario to Seattle with momondo

Alaska Airlines Flights From Ontario to Seattle

Delta Flights From Ontario to Seattle

Traveling to a place near Seattle?

Why use momondo?

Why should I use momondo to find a flight deal from Ontario to Seattle?

Can I find flights from Ontario to Seattle with flexible booking policies on momondo?

How can momondo help me find flights from Ontario to Seattle?

I’m not ready to book a flight from Ontario to Seattle right now. Can momondo alert me if prices change?

An easier way to manage your Seattle trip

We make it super easy to schedule, organize and travel with friends or family. Trips is free — and available to use no matter where you book.

Get notified when prices go down

Daily price changes in your inbox - only with Price Alerts.