Cheap flights from Illinois to Seattle from $142

In general, January is the cheapest month to fly from Illinois to Seattle. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $232. If you don’t want to visit Seattle in January, then you should wait until February to fly from Illinois, when ticket prices are also cheap, with an average price of $239.

On average, the least expensive day to fly to Seattle from Illinois is on a Friday. momondo users have found tickets for Friday departures for as low as $391. 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 Illinois because it is more convenient for both business and leisure travelers. As a result, prices tend to be around $464.

Flying to Seattle from Illinois in the evening is the least expensive time of day to depart. momondo users have found prices as low as $381 when looking at flights departing in the evening. Flights to Seattle are more costly in the afternoon, with an average ticket price of $425. Departure times in the afternoon fall within the peak daily travel times, which is why tickets can be more expensive.

Fly from Chicago O'Hare Intl to Seattle/Tacoma Intl for the best Illinois - Seattle/Tacoma Intl flight prices

You are more likely to see cheaper flights to Seattle from Illinois when booking weeks ahead of your departure date. In general, you can expect to find flights to Seattle for around $330 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Seattle from Illinois for as low as $313 on momondo.

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

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

American Airlines, Alaska Airlines and United Airlines are the top three most popular airlines that fly to Seattle from Illinois according to our data. American Airlines is the first choice among our users, with 30% of people opting to fly with this airline when traveling to Seattle. Keep in mind that there are 6 different airlines that fly to Seattle on a routine basis, so you have a few additional options to choose from.

23 flights are operational daily from Illinois to Seattle as of October 2026. The most popular departure time for this route is 6:00PM, with 46% of flights per day taking off in the evening.

As of October 2026, there are 167 flights per week flying from Illinois to Seattle. The most common day of the week flights depart is Fri, with 31% of flights taking off on this day.