Best Time to Fly STL to BWI: On-Time Stats by Hour & Airline
St Louis Lambert International → Baltimore/Washington International Thurgood Marshall
Data through July 2026 · Last updated October 18, 2026
Over the last 12 months, 80.3% of St. Louis (STL) to Baltimore (BWI) flights arrived on time (1,279 scheduled flights). That is 2.6 points above the national average of 77.6%.
Southwest Airlines was the only reporting airline with regular flights on this route.
Over 24 months, Tuesday was the most reliable day (85% on time) and July the worst month (70%).
The cancellation rate was 1.3% (US average 1.8%).
STL to BWI 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 | 80.3% | 58 min | 1.3% | 1,279 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly STL to BWI
On-time arrival % by scheduled departure hour (local time), 2,596 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 5am–6am | 94.2% | 0.8% | 351 |
| 6am–7am | 92.9% | 1.0% | 297 |
| 7am–8am | 97.2% | 0.0% | 72 |
| 8am–9am | 92.2% | 0.0% | 103 |
| 9am–10am | 90.6% | 0.0% | 213 |
| 10am–11am | 92.6% | 1.8% | 55 |
| 11am–12pm | 90.7% | 0.0% | 86 |
| 12pm–1pm | 87.0% | 0.9% | 116 |
| 1pm–2pm | 72.8% | 5.2% | 97 |
| 2pm–3pm | 80.7% | 0.7% | 137 |
| 3pm–4pm | 80.8% | 1.4% | 74 |
| 4pm–5pm | 69.9% | 2.2% | 137 |
| 5pm–6pm | 68.2% | 2.2% | 182 |
| 6pm–7pm | 71.7% | 2.5% | 204 |
| 7pm–8pm | 64.2% | 0.8% | 121 |
| 8pm–9pm | 66.4% | 1.5% | 267 |
| 9pm–10pm | 54.9% | 2.4% | 84 |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on STL to BWI
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) | 70.2% | -13.3 pts | 0.0% | 47 |
| Christmas & New Year (Dec 20 - Jan 3) | 77.9% | -5.6 pts | 1.0% | 96 |
| Summer peak (Jun 15 - Aug 15) | 73.5% | -9.9 pts | 2.4% | 510 |
| All other days | 83.5% | — | 1.1% | 1,943 |
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).