Skyscanner

Cheap Flights from Ontario (ONT) to Seattle (SEAA)

Travellers and cabin class

Compare Ontario International to Seattle flight deals

Find the cheapest month or even day of the year to fly to Seattle

Book the best Seattle fare with no extra fees

Flight deals from Ontario International to Seattle

Looking for a cheap last-minute deal or the best return flight from Ontario International to Seattle? Find the lowest prices on one-way and return tickets right here.
Seattle.$112 per passenger.Departing Sat, 31 May, returning Wed, 4 Jun.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Sat, 31 May, arriving in Seattle / Tacoma International.Inbound direct flight with Frontier Airlines departs from Seattle / Tacoma International on Wed, 4 Jun, arriving in Ontario International.Price includes taxes and charges.From $112, select.
Seattle.$112 per passenger.Departing Tue, 3 Jun, returning Sat, 7 Jun.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Tue, 3 Jun, arriving in Seattle / Tacoma International.Inbound direct flight with Frontier Airlines departs from Seattle / Tacoma International on Sat, 7 Jun, arriving in Ontario International.Price includes taxes and charges.From $112, select.
Seattle.$157 per passenger.Departing Wed, 28 May, returning Sat, 31 May.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Wed, 28 May, arriving in Seattle / Tacoma International.Inbound direct flight with Frontier Airlines departs from Seattle / Tacoma International on Sat, 31 May, arriving in Ontario International.Price includes taxes and charges.From $157, select.
Seattle.$203 per passenger.Departing Wed, 27 Aug, returning Fri, 5 Sep.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Wed, 27 Aug, arriving in Seattle / Tacoma International.Inbound direct flight with Frontier Airlines departs from Seattle / Tacoma International on Fri, 5 Sep, arriving in Ontario International.Price includes taxes and charges.From $203, select.
Seattle.$239 per passenger.Departing Sat, 12 Jul, returning Wed, 16 Jul.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Sat, 12 Jul, arriving in Seattle / Tacoma International.Inbound direct flight with Frontier Airlines departs from Seattle / Tacoma International on Wed, 16 Jul, arriving in Ontario International.Price includes taxes and charges.From $239, select.
Seattle.$244 per passenger.Departing Fri, 1 Aug, returning Mon, 4 Aug.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Fri, 1 Aug, arriving in Seattle / Tacoma International.Inbound direct flight with Frontier Airlines departs from Seattle / Tacoma International on Mon, 4 Aug, arriving in Ontario International.Price includes taxes and charges.From $244, select.
Seattle.$272 per passenger.Departing Fri, 24 Oct, returning Mon, 27 Oct.Return flight with United.Outbound indirect flight with United, departs from Ontario International on Fri, 24 Oct, arriving in Seattle / Tacoma International.Inbound indirect flight with United, departs from Seattle / Tacoma International on Mon, 27 Oct, arriving in Ontario International.Price includes taxes and charges.From $272, select.
Seattle.$272 per passenger.Departing Thu, 4 Sep, returning Sun, 28 Sep.Return flight with United.Outbound indirect flight with United, departs from Ontario International on Thu, 4 Sep, arriving in Seattle / Tacoma International.Inbound indirect flight with United, departs from Seattle / Tacoma International on Sun, 28 Sep, arriving in Ontario International.Price includes taxes and charges.From $272, select.

Find the cheapest month to fly from Ontario International to Seattle

We’re always keeping an eye on fares, so you can find the best one in seconds. It looks like Ontario International to Seattle flights are currently cheapest in June.
May
from $157
Jun
from $112
Jul
from $239
Aug
from $244
Sep
from $272
Oct
from $272
Nov
from $284
Dec
Find prices
Jan
Find prices
Feb
Find prices
Mar
Find prices
Apr
Find prices

Direct flights from Ontario International to Seattle

Alternative Ontario International to Seattle routes

Looking for the cheapest, fastest or easiest route from Ontario International to Seattle? You could fly into the following airports instead.

Ontario to Seattle: Flight information

The things to know before you go.
Cheapest flight found$112
Cheapest month to flyMay
Average flight time2 hrs, 51 mins
Most popular airlineWestJet
Average flights per week180

Finding cheap flights from Ontario International to Seattle: Frequently asked questions

There are 4 airports in Seattle: Seattle Lake Union SPB, Seattle Boeing Fld, Seattle / Tacoma International, and Paine Field.
The best price we found for a return flight from Ontario International to Seattle is $112. This is an estimate based on information collected from different airlines and travel providers over the last 4 days and is subject to change and availability.
2 hours and 51 minutes is the average flight time from Ontario International to Seattle.
WestJet, Alaska Airlines and Hawaiian Airlines fly direct from Ontario International to Seattle.
As of May 2025, there are 360 flights per week flying from Ontario International to Seattle.
The cheapest month to fly from Ontario International to Seattle is usually May 2025.
If you're flying from Ontario International Airport, the cheapest airport near Seattle is Seattle / Tacoma International – which is 19.5 km away from the centre of Seattle. We've found flights into this airport from $112.
After crunching the numbers on our flight calendar, we found that it's currently cheapest to fly from Ontario International Airport to Seattle on Saturday, 31 May 2025.
Yes – the average flight time is 2 hours and 51 minutes.
We show every price from over 1,200 airlines and travel agents, comparing them all so you don’t have to. If you know you want to fly to Seattle but you’re not ready to book, set up a Price Alert. We’ll track prices for you, and let you know when they rise or fall.
We crunched all the numbers in our flight calendar and it looks like the cheapest time to book a flight to Seattle is around 40 days in advance, so don’t leave your flight to the last minute.
In May, the average temperature is usually around 12°C. August is typically the warmest month in Seattle, when it usually averages around 23°C. You can expect the least rain in July. The coldest month is December, with temperatures averaging 0°C. The rainiest month is November.
Currently, Frontier Airlines offers the cheapest flight tickets to Seattle.

Travelling from Ontario International Airport (ONT) to Seattle: what you need to know

  • Take a direct flight from Ontario International Airport to Seattle and you'll be in the air for an average of 2 hours 40 minutes.

  • Ontario (the location of Ontario International Airport) and Seattle follow the same timezone — UTC-7.

  • Ontario International Airport (ONT) to Seattle-Tacoma International Airport (SEA) is the most popular route, with 53 departures a week to choose from. If you have things to do before leaving, the last flight from ONT to SEA is with Alaska Airlines at 19:24. Opt for the first departure operated by Delta Air Lines at 05:40 if you want to fly out earlier.

  • For a stress-free journey, turn up at the airport two hours ahead of international flights and an hour before domestic departures. This will give you plenty of time to board your ONT to Seattle flight.

  • Longer lines at check-in and security are likely if you're travelling during high season, so allow a little extra breathing room. A good rule for peak periods? Get there up to four hours early for international flights and two hours for domestic departures.

  • Direct Ontario International Airport to Seattle tickets are available for booking. Seattle-Tacoma International Airport (SEA) will be where your journey ends.

  • You'll have your pick of airlines that operate direct flights from Ontario International Airport to Seattle. Book your seat with one of these:

  • The journey from central Ontario to ONT takes around 1 hour 30 minutes by public transport. If you drive, ride-share or take a cab, you'll cover the 5 kilometres in 10 minutes or so, depending on traffic conditions.

  • Searching for a hotel close to ONT? If you're catching an early flight from Ontario International Airport to Seattle, these stays will put you moments from your departure gate:

  • Ontario International Airport has an excellent on-time record, so you're less likely to experience disruptions. Departures from ONT arrive on schedule 83.6% of the time.

  • ONT is located at 2900 E. Airport Drive.

How to find the cheapest flights from Ontario International Airport (ONT) to Seattle

  • $56 is the lowest price we've seen for a one-way Ontario International Airport to Seattle flight. A round-trip flight ticket right now is $112. Depending on how early you book and the availability, these fares can change.

  • Book one month before you want to fly. Pricing trends suggest that this is the ideal window for finding cheap flights from ONT to Seattle.

  • May is the best month for nabbing an awesome deal on Ontario International Airport to Seattle tickets. If you're looking to travel at a different time of year, the 'Whole month' tool will give you the lowest prices for each month.

  • Snapping up a cheap flight from ONT to Seattle is a breeze with Price Alerts. Simply create one of these automatic notifications and we'll let you know as soon as the price has dropped.

  • Choose your preferred departure and arrival times, number of stops and airlines with our filters. Then, sort the results for your flight from Ontario International Airport to Seattle by 'Fastest,' 'Cheapest' or 'Best.'

Airports in Seattle

Seattle-Tacoma International Airport (SEA)

  • The distance from Seattle-Tacoma International Airport (SEA) to central Seattle is roughly 23 kilometres. It'll take you around 20 minutes to reach the centre driving.

  • It takes around 55 minutes if you're using public transport.

  • If you have a late flight from Ontario International Airport to Seattle, few things beat the convenience of staying near the terminal. Pick up your bags from the carousel and then be showered and resting not long after at one of these hotels near SEA:

  • Pick up a Seattle-Tacoma International Airport rental car and explore Seattle and beyond with your own wheels. Thrifty, Europcar and Budget are top outlets to choose from here.

  • For the lowest price, book your vehicle from Seattle-Tacoma International Airport about one week in advance of your flight from ONT to Seattle.

Lake Union Sea Plane Base Airport (LKE)

  • The centre of Seattle is located around 3 kilometres from Lake Union Sea Plane Base Airport (LKE). Once your flight from Ontario International Airport to Seattle has landed and you've made your way to arrivals, expect a drive of about 10 minutes.

  • The journey will take about 25 minutes on public transport.

  • Place the 'Do not disturb' sign on your door and unwind at a hotel near LKE. Here are a few options where you can kick back after your ONT to Seattle flight:

Best time to go to Seattle

  • Carefully consider your dates before securing your flight from Ontario International Airport to Seattle. The city comes alive during high season, but rates are generally higher and top attractions can be busy. Go to Seattle in low season if you like a more relaxed vibe.

  • Lock in an Ontario International Airport to Seattle flight ticket with a departure in August if you want to explore the city during its warmest month. Expect temperatures to range from 12ºC (54ºF) to 28ºC (82ºF).

  • Search for cheap tickets from ONT to Seattle in February if you'd rather travel when it's cooler. Temperatures are at their lowest then, ranging between -1ºC (30ºF) and 11ºC (52ºF) on average.

More about Seattle

  • When it comes to looking for somewhere to rest your head, you'll find the best stays in Seattle right here. Check out these hotels once you've booked your flight from Ontario International Airport to Seattle:

  • All great journeys should include some sightseeing. LMN Architects, Greyhound: Bus Station and Boeing Radiation Effects Lab are must-do's during your Seattle adventure.

Explore more of United States

  • Seattle is always a good idea, but there are so many other corners of United States just waiting to be discovered. Around 241 kilometres south of Seattle, a visit to Portland will keep your itinerary busy. Start with popular sights like Pioneer Courthouse Square, Portland Japanese Garden and Pittock Mansion.

  • Spokane is another favourite destination in United States and is around 370 kilometres east of Seattle. No journey is complete without experiencing Manito Park, Northwest Museum of Arts & Culture and Spokane Falls.

Plan the rest of your trip from Ontario to Seattle

Prices shown on this page are estimated lowest prices only. Found in the last 45 days.