Skyscanner

Cheap flights from Ontario International to Seattle / Tacoma International

Compare Ontario International to Seattle / Tacoma International flight deals

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

Book the best Seattle / Tacoma International fare with no extra fees

Flight deals from Ontario International to Seattle / Tacoma International

Looking for a cheap last-minute deal or the best return flight from Ontario International to Seattle / Tacoma International? Find the lowest prices on one-way and return tickets right here.
Seattle.P6,419 per passenger.Departing Thu, 4 Dec, returning Mon, 8 Dec.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Ontario International on Thu, 4 Dec, arriving in Seattle / Tacoma International.Inbound indirect flight with Frontier Airlines, departs from Seattle / Tacoma International on Mon, 8 Dec, arriving in Ontario International.Price includes taxes and charges.From P6,419, select.
Seattle.P6,484 per passenger.Departing Fri, 21 Nov, returning Sun, 23 Nov.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Fri, 21 Nov, arriving in Seattle / Tacoma International.Inbound direct flight with Frontier Airlines departs from Seattle / Tacoma International on Sun, 23 Nov, arriving in Ontario International.Price includes taxes and charges.From P6,484, select.
Seattle.P7,017 per passenger.Departing Thu, 8 Jan, returning Sat, 10 Jan.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Ontario International on Thu, 8 Jan, arriving in Seattle / Tacoma International.Inbound indirect flight with Frontier Airlines, departs from Seattle / Tacoma International on Sat, 10 Jan, arriving in Ontario International.Price includes taxes and charges.From P7,017, select.
Seattle.P7,192 per passenger.Departing Fri, 19 Dec, returning Sun, 4 Jan.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Fri, 19 Dec, arriving in Seattle / Tacoma International.Inbound direct flight with Frontier Airlines departs from Seattle / Tacoma International on Sun, 4 Jan, arriving in Ontario International.Price includes taxes and charges.From P7,192, select.
Seattle.P8,754 per passenger.Departing Sun, 21 Dec, returning Tue, 30 Dec.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Sun, 21 Dec, arriving in Seattle / Tacoma International.Inbound direct flight with Frontier Airlines departs from Seattle / Tacoma International on Tue, 30 Dec, arriving in Ontario International.Price includes taxes and charges.From P8,754, select.
Seattle.P9,343 per passenger.Departing Mon, 5 Jan, returning Fri, 9 Jan.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Mon, 5 Jan, arriving in Seattle / Tacoma International.Inbound direct flight with Frontier Airlines departs from Seattle / Tacoma International on Fri, 9 Jan, arriving in Ontario International.Price includes taxes and charges.From P9,343, select.
Seattle.P9,637 per passenger.Departing Wed, 26 Nov, returning Mon, 1 Dec.Return flight with Frontier Airlines.Outbound direct flight with Frontier Airlines departs from Ontario International on Wed, 26 Nov, arriving in Seattle / Tacoma International.Inbound direct flight with Frontier Airlines departs from Seattle / Tacoma International on Mon, 1 Dec, arriving in Ontario International.Price includes taxes and charges.From P9,637, select.
Seattle.P10,322 per passenger.Departing Tue, 27 Jan, returning Tue, 3 Feb.Return flight with Delta.Outbound direct flight with Delta departs from Ontario International on Tue, 27 Jan, arriving in Seattle / Tacoma International.Inbound direct flight with Delta departs from Seattle / Tacoma International on Tue, 3 Feb, arriving in Ontario International.Price includes taxes and charges.From P10,322, select.

Find the cheapest month to fly from Ontario International to Seattle / Tacoma International

We’re always keeping an eye on fares, so you can find the best one in seconds. It looks like Ontario International to Seattle / Tacoma International flights are currently cheapest in December.
Nov
from P6,484
Dec
from P6,419
Jan
from P7,017
Feb
from P11,542
Mar
from P13,250
Apr
from P19,619
May
from P16,333
Jun
from P16,280
Jul
from P19,835
Aug
Find prices
Sep
Find prices
Oct
Find prices

Direct flights from Ontario International to Seattle / Tacoma International

Ontario International to Seattle / Tacoma International: Alternative routes

Compare routes from Ontario International to Seattle below. You may find an airport to fly into that's cheaper, faster, or easier than Seattle / Tacoma International.

Ontario to Seattle: Flight information

The things to know before you go.
Cheapest flight foundP6,419
Cheapest month to flyDecember
Average flight time2 hrs, 57 mins
Most popular airlineAlaska Airlines
Average flights per week118

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

The best price we found for a return flight from Ontario International to Seattle / Tacoma International is P6,419. 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 57 minutes is the average flight time from Ontario International to Seattle / Tacoma International.
Alaska Airlines, Hawaiian Airlines and Qatar Airways fly direct from Ontario International to Seattle / Tacoma International.
As of November 2025, there are 118 flights per week flying from Ontario International to Seattle / Tacoma International.
The cheapest month to fly from Ontario International to Seattle / Tacoma International is usually December.
After crunching the numbers on our flight calendar, we found that it's currently cheapest to fly from Ontario International Airport to Seattle / Tacoma International Airport on Thursday, 4 December 2025.
Yes – the average flight time is 2 hours and 57 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 / Tacoma International 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.
Currently, Frontier Airlines offers the cheapest flight tickets to Seattle / Tacoma International.

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

  • The average time for a direct flight from Ontario International Airport to Seattle-Tacoma International Airport is 2 hours 45 minutes.

  • Ontario and Seattle share the UTC-7 timezone. This means you won't need to account for any time differences.

  • Flights from ONT to SEA start from 06:00 — the earliest with Alaska Airlines. The latest departure is at 21:09 with Alaska Airlines. In total, there are 67 weekly Ontario International Airport to Seattle-Tacoma International Airport flights.

  • Arriving two hours before an international flight and one hour ahead of a domestic departure are tried-and-true travel tips. Make sure you're at the airport on time to board your ONT to SEA flight.

  • During popular months like August, you'll want to get to the airport well in advance. Arrive two hours before a domestic departure and four hours ahead for international flights when you fly during a high season in general.

  • With direct flights from Ontario International Airport to Seattle-Tacoma International Airport operated by a number of airlines, getting to Seattle (and then other corners of United States) is a cinch. You can travel nonstop with:

  • The airline with the highest booking volume on this route is Alaska Airlines.

  • With a reliable 90.0% of services arriving as scheduled, Frontier Airlines is the most punctual carrier offering ONT to SEA flights.

  • If you want to break up your flight, just uncheck 'Direct flights only' when searching for your ticket from Ontario International Airport to Seattle-Tacoma International Airport. Here are the most popular stopovers between ONT and SEA:

    • Sacramento International Airport

    • Metropolitan Oakland International Airport

    • Portland International Airport

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

  • P2,845 is currently the best price for a one-way Ontario International Airport to Seattle-Tacoma International Airport flight. A return flight starts at P6,419. These prices may change based on availability.

  • To get cheap tickets from ONT to SEA, reserve your trip six months ahead of your planned departure.

  • Plan your trip for May. That's the cheapest month for flights from Ontario International Airport to Seattle-Tacoma International Airport. If you're flexible with your dates, try out the 'Whole month' tool to find the cheapest airfare across every month.

  • Picking up cheap flights from ONT to SEA is a breeze with Price Alerts. All you need to do is set up one of these automatic alerts and we'll notify you as soon as a new deal comes up.

  • Discover the ideal flight for you with the help of the filters. To see the 'Fastest,' 'Best' or 'Cheapest' flights from Ontario International Airport to Seattle-Tacoma International Airport, use the 'Sort by' tool. You can also filter by arrival and departure times, airline, and number of stops.

Handy information about Ontario International Airport (ONT)

  • The address for ONT is 2900 E. Airport Drive.

  • Ontario International Airport scores high marks for on-time performance. 83.6% of flights that take off from ONT reach their destination without delay.

  • To get to Ontario International Airport from central Ontario, it takes about 10 minutes if you're going by car. This depends on traffic, however. It's approximately 6 kilometres from the airport to the city centre.

  • The journey when using public transport typically takes 1 hour 30 minutes.

  • Get your travels off to a stress-free start by staying near ONT. Whether you're boarding an early flight from Ontario International Airport to Seattle-Tacoma International Airport or just don't like being rushed, these stays have you covered:

Arriving at Seattle-Tacoma International Airport (SEA)

Getting from Seattle-Tacoma International Airport (SEA) to central Seattle

  • From Seattle-Tacoma International Airport, Seattle is approximately 23 kilometres away. It takes around 20 minutes to reach the centre by car.

  • Travelling on public transport will take you roughly 55 minutes.

When to fly to Seattle-Tacoma International Airport (SEA)

  • The quietest month for a flight from Ontario International Airport to Seattle-Tacoma International Airport is May, while July is the busiest. Pick the best time to go to Seattle based on whether you prefer a more fast-paced or easygoing experience.

  • The warmest month in Seattle is August, with temperatures ranging between 12ºC (54ºF) and 28ºC (82ºF). Book your flights from Ontario International Airport to Seattle-Tacoma International Airport in this month if you enjoy this type of weather.

  • Look for cheap tickets from ONT to SEA in February if you like cooler conditions. Temperatures are at their lowest around then, ranging between -1ºC (30ºF) and 11ºC (52ºF) on average.

Explore more of United States

  • Seattle has plenty going for it, but there are so many other corners of United States waiting to be discovered. Around 241 kilometres south of Seattle, a visit to Portland will keep you busy. Start with popular sights like Pioneer Courthouse Square, Portland Japanese Garden and Pittock Mansion.

  • Spokane is another standout 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.

More travel options

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