Cheap flights from Montana to Illinois from $138

The cheapest month to fly to Illinois from Montana is in January. Flight prices, which tend to average around $310, 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 January, then flying in February is also cheap. Prices for this month can be found on momondo for an average of $344.

The cheapest day to depart from Montana to Illinois is on a Thursday when prices can be found for as low as $441. Flights from Montana to Illinois on a Sunday will generally be more expensive and average around $645. 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 at noon. Flights from Montana to Illinois during this time can be as low as $444. Flights in the morning are often more expensive with an average ticket price of $489.

Fly from Bozeman Gallatin Field to Chicago O'Hare Intl for the best Montana - Illinois flight prices

You are more likely to see cheaper flights to Illinois from Montana when booking weeks ahead of your departure date. In general, you can expect to find flights to Illinois for around $382 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Illinois from Montana for as low as $292 on momondo.

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

Delta, United Airlines, and Alaska Airlines are the most popular carriers operating from Montana to Illinois

United Airlines, American Airlines and Delta are the top three most popular airlines that fly to Illinois from Montana according to our data. United Airlines is the first choice among our users, with 54% of people opting to fly with this airline when traveling to Illinois. Keep in mind that there are 3 different airlines that fly to Illinois on a routine basis, so you have a few additional options to choose from.

As of October 2026, 8 flights take off from Montana and land in Illinois each day. The most common flight departure time for this route is 12:00PM, with 88% of daily flights taking off in the afternoon.

As of October 2026, 57 flights take off from Montana and land in Illinois each week. The most common flight departure day for this route is Wed, with 32% of weekly flights taking off on this day.