Best Time to Fly MDW to STL: On-Time Stats by Hour & Airline
Chicago Midway International → St Louis Lambert International
Data through July 2026 · Last updated October 18, 2026
Over the last 12 months, 82.0% of Chicago (MDW) to St. Louis (STL) flights arrived on time (1,708 scheduled flights). That is 4.3 points above the national average of 77.6%.
Southwest Airlines was the only reporting airline with regular flights on this route.
October has been the best month (91% on time) and Sunday the weakest day of the week (80%).
1.3% of flights were cancelled, versus 1.8% nationally.
MDW to STL on-time performance by airline
Last 12 months. Airlines with fewer than 30 completed flights are marked “limited data”.
| Airline | On time | Avg delay when late | Cancelled | Flights |
|---|---|---|---|---|
| Southwest Airlines | 82.0% | 60 min | 1.3% | 1,708 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly MDW to STL
On-time arrival % by scheduled departure hour (local time), 3,519 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 5am–6am | 100.0% | 1.3% | 76 |
| 6am–7am | 97.1% | 0.3% | 282 |
| 7am–8am | 92.1% | 0.7% | 282 |
| 8am–9am | 95.7% | 0.0% | 164 |
| 9am–10am | 94.6% | 2.2% | 320 |
| 10am–11am | 91.0% | 1.5% | 136 |
| 11am–12pm | 85.1% | 2.4% | 255 |
| 12pm–1pm | 87.1% | 1.9% | 103 |
| 1pm–2pm | 89.5% | 0.7% | 279 |
| 2pm–3pm | 75.9% | 0.8% | 259 |
| 3pm–4pm | 73.3% | 0.0% | 45 |
| 4pm–5pm | 78.9% | 1.6% | 125 |
| 5pm–6pm | 69.3% | 1.4% | 221 |
| 6pm–7pm | 72.8% | 0.0% | 180 |
| 7pm–8pm | 79.2% | 0.5% | 213 |
| 8pm–9pm | 78.4% | 1.3% | 225 |
| 9pm–10pm | 67.2% | 1.2% | 256 |
| 10pm–11pm | 74.0% | 2.0% | 98 |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on MDW to STL
On-time arrivals during holiday periods compared with all other days, last 24 months.
| Period | On time | vs other days | Cancelled | Flights |
|---|---|---|---|---|
| Thanksgiving week (Tue before to Mon after) | 75.0% | -11.2 pts | 4.8% | 63 |
| Christmas & New Year (Dec 20 - Jan 3) | 81.0% | -5.1 pts | 0.7% | 138 |
| Summer peak (Jun 15 - Aug 15) | 76.3% | -9.8 pts | 1.6% | 678 |
| All other days | 86.2% | — | 0.9% | 2,640 |
Monthly on-time trend
On-time arrival % each month, with the 12-month US average for reference.
What causes delays on this route
Share of reported delay minutes, last 12 months (BTS cause categories).