Cheap flights from South Dakota to Illinois from $126

The cheapest month to fly to Illinois from South Dakota is in April. Flight prices, which tend to average around $151, 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 April, then flying in September is also cheap. Prices for this month can be found on momondo for an average of $154.

The cheapest day to depart from South Dakota to Illinois is on a Saturday when prices can be found for as low as $439. Flights from South Dakota to Illinois on a Sunday will generally be more expensive and average around $611. 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 morning. Flights from South Dakota to Illinois during this time can be as low as $452. Flights at noon are often more expensive with an average ticket price of $479.

Fly from Watertown to Chicago O'Hare Intl for the best South Dakota - Illinois flight prices

You are more likely to see cheaper flights to Illinois from South Dakota when booking weeks ahead of your departure date. In general, you can expect to find flights to Illinois for around $303 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Illinois from South Dakota for as low as $169 on momondo.

As of May 2026, there are 28 flights per day flying from South Dakota to Illinois. The most common time of day flights depart is 12:00PM, with 44% of flights taking off in the afternoon.

The number of flights available between South Dakota and Illinois is 200 per week as of May 2026. The most frequent departure day is Wed, with 15% of weekly flights leaving on this day.