Cheap flights from Washington to Illinois from $159

The cheapest month to fly to Illinois from State of Washington is in February. Flight prices, which tend to average around $275, are often lower during this time because this is during the off-season. If you aren’t able to travel to Illinois during the month of February, then flying in January is also cheap. Prices for this month can be found on momondo for an average of $287.

The cheapest day to depart from State of Washington to Illinois is on a Wednesday when prices can be found for as low as $434. Flights from State of Washington to Illinois on a Sunday will generally be more expensive and average around $524. Keep in mind that these prices on both days could fluctuate depending on the season and the demand.

Our most recent data shows that the best time of day to fly to Illinois is in the afternoon. Flights from State of Washington to Illinois during this time can be as low as $382. Flights at noon are often more expensive with an average ticket price of $488.

Fly from Seattle/Tacoma Intl to Chicago Midway for the best Washington - Illinois flight prices

You are more likely to see cheaper flights to Illinois from State of Washington when booking weeks ahead of your departure date. In general, you can expect to find flights to Illinois for around $349 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Illinois from State of Washington for as low as $288 on momondo.

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

Delta, Southwest, and Alaska Airlines are the most popular carriers operating from Washington to Illinois

American Airlines, Alaska Airlines and United Airlines are the top three most popular airlines that fly to Illinois from State of Washington according to our data. American Airlines is the first choice among our users, with 31% of people opting to fly with this airline when traveling to Illinois. Keep in mind that there are 6 different airlines that fly to Illinois on a routine basis, so you have a few additional options to choose from.

42 flights are operational daily from State of Washington to Illinois as of September 2026. The most popular departure time for this route is 6:00AM, with 62% of flights per day taking off at noon.

As of September 2026, 295 flights take off from State of Washington and land in Illinois each week. The most common flight departure day for this route is Fri, with 22% of weekly flights taking off on this day.