St. Louis (STL) to Houston (IAH): On-Time Performance
Data through May 2026
The calendar drives reliability on STL–IAH. September 2025 flights landed on schedule 94% of the time, but July 2024 dropped to 51% — a gap of 43 points. Across the full period the route averages 78% on-time against a national 78%. Morning departures also hold up better than evening ones (84% vs 60%), which matters most in the rough months.
- On-time
- 78%
- arrived <15 min late
- Avg delay
- 20 min
- completed flights
- Cancelled
- 1.6%
- Flights/day
- 1.3
- last 12 months
- Duration
- 2h 15m
- scheduled
- Distance
- 667 mi
Best airline from STL to IAH
2 airlines flew this route regularly between 2024-06 and 2026-05.
| Airline | On-time | Avg delay | Cancelled | Flights |
|---|---|---|---|---|
| United Airlinesmost reliable | 78% | 18 min | 1.8% | 1,042 |
| SkyWest Airlines | 76% | 28 min | 0.0% | 153 |
Monthly on-time trend
Best time to fly from STL to IAH
Aim for departures around 6 a.m. (85% on-time); avoid 5 p.m. departures (57%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Mondaybest | 82% | 31 min |
| Tuesday | 81% | 11 min |
| Wednesday | 74% | 17 min |
| Thursday | 77% | 19 min |
| Friday | 80% | 19 min |
| Saturday | 75% | 16 min |
| Sunday | 74% | 22 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft42%
- Airline operations35%
- National airspace system21%
- Weather3%
Frequently asked questions
- How often are flights from STL to IAH delayed?
- 22% of STL–IAH flights arrived 15 or more minutes late (the US DOT definition of a delay) between 2024-06 and 2026-05. The average arrival delay across completed flights was 20 minutes.
- Which airline is most reliable from STL to IAH?
- United Airlines has the best on-time record on this route at 78%, based on 1,042 flights. 2 airlines flew STL–IAH frequently enough to compare in this period.
- What is the best time of day to fly from STL to IAH?
- Departures around 6 a.m. have the best record (85% on-time), while departures around 5 p.m. have the worst (57%). As on most US routes, delays accumulate through the day, so earlier flights are generally safer.
- How long is the flight from STL to IAH?
- The scheduled STL–IAH flight time averages 2h 15m over 667 miles. Actual arrival times vary — flights on this route land 15+ minutes late 22% of the time.
- How often are STL to IAH flights cancelled?
- 1.6% of scheduled flights on this route were cancelled between 2024-06 and 2026-05, at or below the national rate of 1.6%.
- What is the worst month to fly from STL to IAH?
- July 2024 was the roughest month in this dataset, with only 51% of arrivals on time. The best was September 2025 at 94%. If your dates are flexible, that 43-point gap is worth planning around.
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Based on 1,195 flights, 2024-06–2026-05. Source: US DOT Bureau of Transportation Statistics. Updated 2026-07-01.