Houston, TX

What the Data Says About IAH

Houston, TX in Houston, Texas handled 1,404,392 flights in the Bureau of Transportation Statistics dataset between 2020 and 2025, posting a 81.6% on-time departure rate. Of those flights, 258,419 experienced delays, 15,858 were cancelled, and 1,741 were diverted. The cancellation rate works out to 1.13%, the diversion rate to 0.12%, and the average delay when departures run late is 79.8 minutes. These figures are the baseline for comparing IAH against other airports in the same state and nationally.

Breaking down what drives delays at IAH, Carrier leads the pack. Carrier accounts for 38.4% of total delay minutes, followed by Late Aircraft at 34.9% and NAS (National Aviation System) at 18.1%. Weather contributes 8.6% of delay minutes at this airport, while security holds the smallest share at 0.0%. Travelers often overestimate the weather share; the BTS categorization shows late-arriving aircraft and carrier operations as the larger contributors.

Seasonally, September runs the cleanest at IAH with a 92.8% on-time rate, while July is the roughest at 86.4% — a 6-point swing between best and worst month. Volume peaks in March, when average flights hit 21,723. The busiest route from IAH is to DFW (Dallas/Fort Worth), with 30,197 flights at a 76.6% on-time rate. Combine these numbers — 81.6% on-time, 79.8-minute average delay, 1.13% cancellation rate — and you have a concrete picture of departure reliability at Houston, TX.