148 - 292 USD
From most locations, the cheapest flights to Illinois can be found during the month of February; however great deals can be found at other times.
Most flyers found that booking flight tickets 60 days in advance of their planned departure date is, on average, the best time to get cheap flights to Illinois.
On average, the cheapest flights to Illinois are found when departing on a Tuesday. Try to avoid departing on a Sunday, as this is usually the most expensive day.
Generally, when visiting Illinois, evening flights represent the best value. afternoon flights are likely to have higher prices.