St. Louis (STL) to Chicago (MDW): On-Time Performance
Data through May 2026
St. Louis (STL) to Chicago (MDW) effectively runs on two schedules. In November 2024, 92% of arrivals were on time; in July 2025 that fell to 68% — a 24-point seasonal swing. Across the full period the route averages 83% on-time against a national 78%. Morning departures also hold up better than evening ones (90% vs 74%), which matters most in the rough months.
- On-time
- 83%
- arrived <15 min late
- Avg delay
- 10 min
- completed flights
- Cancelled
- 1.1%
- Flights/day
- 4.7
- last 12 months
- Duration
- 1h 9m
- scheduled
- Distance
- 251 mi
Monthly on-time trend
Best time to fly from STL to MDW
Aim for departures around 5 a.m. (95% on-time); avoid 10 p.m. departures (63%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Monday | 81% | 11 min |
| Tuesdaybest | 88% | 9 min |
| Wednesday | 87% | 8 min |
| Thursday | 80% | 11 min |
| Friday | 83% | 10 min |
| Saturday | 83% | 10 min |
| Sunday | 79% | 13 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft55%
- Airline operations24%
- National airspace system18%
- Weather3%
Frequently asked questions
- How often are flights from STL to MDW delayed?
- 17% of STL–MDW 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 10 minutes.
- What is the best time of day to fly from STL to MDW?
- Departures around 5 a.m. have the best record (95% on-time), while departures around 10 p.m. have the worst (63%). As on most US routes, delays accumulate through the day, so earlier flights are generally safer.
- How long is the flight from STL to MDW?
- The scheduled STL–MDW flight time averages 1h 9m over 251 miles. Actual arrival times vary — flights on this route land 15+ minutes late 17% of the time.
- How often are STL to MDW flights cancelled?
- 1.1% 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 MDW?
- July 2025 was the roughest month in this dataset, with only 68% of arrivals on time. The best was November 2024 at 92%. If your dates are flexible, that 24-point gap is worth planning around.
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Based on 3,549 flights, 2024-06–2026-05. Source: US DOT Bureau of Transportation Statistics. Updated 2026-07-01.