Cheap flights from Ontario to Seattle from $99

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 $197. 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 $216.

On average, the least expensive day to fly to Seattle from Ontario is on a Thursday. momondo users have found tickets for Thursday departures for as low as $289. However, this price may fluctuate depending on the airline, the season, and holidays. On the other hand, Monday 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 $382.

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 $270 when looking at flights departing in the afternoon. Flights to Seattle are more costly in the morning, with an average ticket price of $350. Departure times in the morning fall within the peak daily travel times, which is why tickets can be more expensive.

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

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 $251 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 $205 on momondo.

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

Alaska Airlines is the most popular carrier operating from Ontario to Seattle/Tacoma Intl

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 51% 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.

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 130 minutes.

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.

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

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.

The number of flights available between Ontario and Seattle is 20 per day as of July 2026. The most frequent departure time is 6:00AM, with 56% of daily flights leaving at noon.

As of July 2026, there are 140 flights per week flying from Ontario to Seattle. The most common day of the week flights depart is Sun, with 20% of flights taking off on this day.