Best Time to Fly STL to BOS: On-Time Stats by Hour & Airline
St Louis Lambert International → Logan International
Data through July 2026 · Last updated October 18, 2026
1,611 flights were scheduled from St. Louis (STL) to Boston (BOS) in the last 12 months, and 69.7% of those that flew arrived on time, 8.0 points below the US average of 77.6%.
Envoy Air was the most punctual of the 3 airlines on the route at 76.3%, while Southwest Airlines trailed at 65.6%.
February has been the best month (83% on time) and Thursday the weakest day of the week (68%).
1.7% of flights were cancelled, versus 1.8% nationally.
STL to BOS 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 |
|---|---|---|---|---|
| Envoy Air | 76.3% | 78 min | 2.1% | 384 |
| Republic Airways | 74.0% | 92 min | 4.1% | 293 |
| Southwest Airlines | 65.6% | 60 min | 0.8% | 934 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly STL to BOS
On-time arrival % by scheduled departure hour (local time), 3,200 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 7am–8am | 91.9% | 2.1% | 239 |
| 8am–9am | 90.2% | 0.0% | 204 |
| 9am–10am | 88.9% | 2.1% | 385 |
| 10am–11am | 84.4% | 0.5% | 208 |
| 11am–12pm | 76.7% | 1.3% | 239 |
| 12pm–1pm | 65.8% | 2.5% | 81 |
| 1pm–2pm | 73.2% | 0.5% | 207 |
| 2pm–3pm | 61.4% | 1.9% | 481 |
| 3pm–4pm | 53.6% | 2.0% | 99 |
| 4pm–5pm | Limited data | 13 | |
| 5pm–6pm | 67.2% | 2.2% | 137 |
| 6pm–7pm | 73.3% | 1.8% | 339 |
| 7pm–8pm | 57.5% | 2.0% | 358 |
| 8pm–9pm | 64.7% | 1.0% | 200 |
| 9pm–10pm | Limited data | 10 | |
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 BOS
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) | 73.0% | -1.7 pts | 3.1% | 65 |
| Christmas & New Year (Dec 20 - Jan 3) | 81.1% | +6.3 pts | 1.5% | 134 |
| Summer peak (Jun 15 - Aug 15) | 65.8% | -8.9 pts | 2.3% | 598 |
| All other days | 74.7% | — | 1.3% | 2,403 |
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).