St. Louis, MO

What the Data Says About STL

St. Louis, MO in St. Louis, Missouri handled 687,272 flights in the Bureau of Transportation Statistics dataset between 2020 and 2025, posting a 81.3% on-time departure rate. Of those flights, 128,602 experienced delays, 8,116 were cancelled, and 719 were diverted. The cancellation rate works out to 1.18%, the diversion rate to 0.10%, and the average delay when departures run late is 66.7 minutes. These figures are the baseline for comparing STL against other airports in the same state and nationally.

Breaking down what drives delays at STL, Late Aircraft leads the pack. Late Aircraft accounts for 44.1% of total delay minutes, followed by Carrier at 33.9% and NAS (National Aviation System) at 17.9%. Weather contributes 4.0% of delay minutes at this airport, while security holds the smallest share at 0.1%. 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 STL with a 92.3% on-time rate, while July is the roughest at 86.4% — a 6-point swing between best and worst month. Volume peaks in July, when average flights hit 10,502. The busiest route from STL is to DEN (Denver), with 20,999 flights at a 79.9% on-time rate. Combine these numbers — 81.3% on-time, 66.7-minute average delay, 1.18% cancellation rate — and you have a concrete picture of departure reliability at St. Louis, MO.