Chicago, IL

What the Data Says About MDW

Chicago, IL in Chicago, Illinois handled 880,912 flights in the Bureau of Transportation Statistics dataset between 2020 and 2025, posting a 78.4% on-time departure rate. Of those flights, 190,033 experienced delays, 12,896 were cancelled, and 1,057 were diverted. The cancellation rate works out to 1.46%, the diversion rate to 0.12%, and the average delay when departures run late is 59.1 minutes. These figures are the baseline for comparing MDW against other airports in the same state and nationally.

Breaking down what drives delays at MDW, Late Aircraft leads the pack. Late Aircraft accounts for 41.8% of total delay minutes, followed by Carrier at 38.5% and NAS (National Aviation System) at 16.2%. Weather contributes 3.3% of delay minutes at this airport, while security holds the smallest share at 0.2%. Travelers often overestimate the weather share; the BTS categorization shows late-arriving aircraft and carrier operations as the larger contributors.

Seasonally, February runs the cleanest at MDW with a 91% on-time rate, while July is the roughest at 82% — a 9-point swing between best and worst month. Volume peaks in July, when average flights hit 14,409. The busiest route from MDW is to MDW (Chicago), with 19,666 flights at a 81.1% on-time rate. Combine these numbers — 78.4% on-time, 59.1-minute average delay, 1.46% cancellation rate — and you have a concrete picture of departure reliability at Chicago, IL.