Open interactive map →Cheap flights from Seattle to Ontario
Cheap flights from Seattle to Ontario, United States currently start at €62. Multiple carriers serve this route at competitive fares. Non-stop flights are available on this route, cutting total travel time significantly. Browse the month-by-month price calendar below to find when fares are lowest, then click through to book.
Price patterns on the Seattle to Ontario route tend to spike during school holidays and public holiday weekends. Booking 4-6 weeks out generally balances availability and price well on this route. If your travel dates are flexible, check the price calendar for the lowest-priced months before searching for specific flights.
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Cheapest month to fly
- October 2026€62DirectCheapest
Based on tracked fares, October is the cheapest month to fly this route at around €62.
Prices last updated: September 2026
Entry requirements for United States
EU passportESTA required (visa-waiver)
US passportN/A (domestic)
Requirements vary by nationality and change without notice. Check requirements for your nationality →
Alternative routes
Other ways to reach Ontario
Frequently asked questions
How much does a flight from Seattle to Ontario cost?
The cheapest fare currently available from Seattle to Ontario is €62. Prices on this route vary by season, day of week, and how far in advance you book. The month-by-month price calendar on this page shows exactly when fares are highest and lowest, so you can pick the most cost-effective window before searching for specific dates. Fares are refreshed regularly as our flight partners publish new availability.
Are there direct flights from Seattle to Ontario?
Yes - non-stop flights are currently available from Seattle to Ontario. The cheapest direct fare starts at €62, making it a convenient option if you want to avoid layover time. Direct flights are generally quicker and less stressful, especially for shorter trips to United States. Click through to the booking site to check live availability and schedules for your dates.
When is the cheapest time to fly from Seattle to Ontario?
Prices on this route typically dip during shoulder-season months, away from school holidays and public holiday windows. Mid-week departures - particularly Tuesday to Thursday - tend to be cheaper than flights on Fridays and Sundays from Seattle. The month-by-month price calendar above is the fastest way to identify the cheapest window - look for the months with the lowest fares before committing to travel dates. Booking 3-6 weeks in advance generally offers the best balance of price and seat availability on this route.