Cheap flights from Ontario to Seattle from $78
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 7/8. 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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Frontier flights from Ontario to Seattle
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Alaska Airlines flights from Ontario to Seattle
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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 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 $156. If you don’t want to visit Seattle in January, then you should wait until October to fly from Ontario, when ticket prices are also cheap, with an average price of $160.
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 Saturday. momondo users have found tickets for Saturday departures for as low as $252. 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 $342.
What is the cheapest time of day to depart on your flight to Seattle?
Flying to Seattle from Ontario at noon is the least expensive time of day to depart. momondo users have found prices as low as $245 when looking at flights departing at noon. Flights to Seattle are more costly in the morning, with an average ticket price of $310. 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 4 weeks ahead of your departure date. In general, you can expect to find flights to Seattle for around $194 when searching 4 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 $158 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.
What is the cheapest airline that flies from Ontario to Seattle/Tacoma Intl?
Frontier, Delta, and Alaska Airlines are the most popular carriers operating from Ontario to Seattle/Tacoma Intl
What airlines fly to Seattle?
Alaska Airlines, Delta and Frontier 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 49% 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.
How many flights depart from Ontario to Seattle on average per day?
The number of flights available between Ontario and Seattle is 20 per day as of June 2025. The most frequent departure time is 6:00AM, with 74% of daily flights leaving at noon.
How many flights depart from Ontario to Seattle on average per week?
As of June 2025, there are 142 flights per week flying from Ontario to Seattle. The most common day of the week flights depart is Thu, with 16% 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
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 37m.
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 6 as of June 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 737-900 Passenger/BBJ3 (winglets) (17.05% of total bookings). The next most popular plane models are Airbus A320neo (15.92%), Boeing 737-800 Passenger/BBJ2 (winglets) (15.56%), and Boeing 737 MAX 9 (11.99%).
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 (44% of total bookings). The next most popular airlines are Alaska Airlines (33%), Delta (19%), and Hawaiian Airlines (3%).
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 | ||
|---|---|---|---|---|---|
| PriceFrom $65 | Free Cancellation | Rating 5.9 3,295 reviews | |||
| PriceFrom $70 | Free Cancellation | Rating 6.3 8,052 reviews | |||
| PriceFrom $96 | Free Cancellation | Rating 7.8 2,494 reviews | |||
| PriceFrom $114 | Free Cancellation | Rating 8.0 7,946 reviews | |||
| PriceFrom $139 | Free Cancellation | Rating 8.0 10,000 reviews | |||
| PriceFrom $150 | Free Cancellation | Rating 8.0 4,287 reviews |
Delta Flights From Ontario to Seattle
Delta flight deals from Ontario to Seattle start from $114 round-trip. Over the 24 Delta flights for this route in a normal week, average airfare is usually $246 round-trip - but some users have found much cheaper deals with momondo.
Alaska Airlines Flights From Ontario to Seattle
$139 is the best Alaska Airlines flight deal from Ontario to Seattle found on momondo over the last 72 hours. The average Alaska Airlines ticket price found was closer to $263, however, with flight time and availability significantly affecting the price. Alaska Airlines (8.0/10 from 10,000 user reviews) flies into Seattle from Ontario 12 times in an average week so prices can vary.
Traveling to a place near Seattle?
Book flights to Seattle if you plan to visit one of these locationsWhy 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.