Cheap flights from Seattle to Los Angeles from C$ 135

The month of October is, on average, the cheapest month to fly to Ontario from Seattle, with most prices found around C$ 256. The month of September is another great option to travel to Ontario, with average flight prices from Seattle averaging around C$ 282.

On average, the least expensive day to fly to Ontario from Seattle is on a Sunday. momondo users have found tickets for Sunday departures for as low as C$ 168. However, this price may fluctuate depending on the airline, the season, and holidays. On the other hand, Friday is the most expensive day to depart from Seattle because it is more convenient for both business and leisure travellers. As a result, prices tend to be around C$ 413.

Our data shows that the cheapest Seattle to Ontario flights are usually those with departure times in the evening. Our users have found flights to Ontario in the evening for as low as C$ 256. Try not to purchase tickets at noon because they tend to be around C$ 389. Of course, these prices can vary depending on the time of year and what airport you fly to.

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

You are more likely to see cheaper flights to Ontario from Seattle when booking weeks ahead of your departure date. In general, you can expect to find flights to Ontario for around C$ 347 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Ontario from Seattle for as low as C$ 263 on momondo.

There is only 1 cabin class available to choose from on Seattle/Tacoma Intl to Ontario flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

No. A direct flight is the cheapest option for a flight between Seattle to Ontario.

As of March 2026, prices for Seattle to Ontario flights are approximately 21% cheaper when compared to flights at the same time last year.

Alaska Airlines and Delta are the most popular carriers operating from Seattle/Tacoma Intl to Ontario

Frontier, Alaska Airlines and Hawaiian Airlines are the top three most popular airlines that fly to Ontario from Seattle according to our data. Frontier is the first choice among our users, with 55% of people opting to fly with this airline when travelling to Ontario. Keep in mind that there are 5 different airlines that fly to Ontario on a routine basis, so you have a few additional options to choose from.

As of March 2026, 9 flights take off from Seattle and land in Ontario each day. The most common flight departure time for this route is 7:00p.m., with 50% of daily flights taking off in the evening.

The number of flights available between Seattle and Ontario is 69 per week as of March 2026. The most frequent departure day is Fri, with 25% of weekly flights leaving on this day.