Best Time to Fly BOS to STL: On-Time Stats by Hour & Airline
Logan International → St Louis Lambert International
Data through July 2026 · Last updated October 18, 2026
Over the last 12 months, 76.2% of Boston (BOS) to St. Louis (STL) flights arrived on time (1,612 scheduled flights). That is 1.4 points below the national average of 77.6%.
Envoy Air was the most punctual of the 3 airlines on the route at 82.3%, while Southwest Airlines trailed at 72.7%.
November has been the best month (88% on time) and Sunday the weakest day of the week (74%).
1.6% of flights were cancelled, versus 1.8% nationally.
BOS 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 |
|---|---|---|---|---|
| Envoy Air | 82.3% | 73 min | 1.0% | 384 |
| Republic Airways | 79.5% | 56 min | 4.1% | 293 |
| Southwest Airlines | 72.7% | 60 min | 1.0% | 935 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly BOS to STL
On-time arrival % by scheduled departure hour (local time), 3,198 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 5am–6am | 94.9% | 0.0% | 176 |
| 6am–7am | 93.3% | 2.9% | 511 |
| 7am–8am | 94.0% | 0.2% | 520 |
| 8am–9am | 90.6% | 0.8% | 130 |
| 9am–10am | 79.7% | 4.5% | 67 |
| 10am–11am | 84.8% | 0.8% | 119 |
| 11am–12pm | 87.5% | 1.8% | 222 |
| 12pm–1pm | 79.6% | 1.4% | 144 |
| 1pm–2pm | 75.2% | 0.0% | 150 |
| 2pm–3pm | 73.1% | 0.0% | 134 |
| 3pm–4pm | 71.1% | 1.1% | 184 |
| 4pm–5pm | 64.7% | 3.3% | 214 |
| 5pm–6pm | 60.2% | 3.1% | 194 |
| 6pm–7pm | 47.5% | 2.2% | 227 |
| 7pm–8pm | 51.0% | 1.5% | 204 |
| 8pm–9pm | Limited data | 2 | |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on BOS 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) | 83.3% | +2.9 pts | 1.5% | 67 |
| Christmas & New Year (Dec 20 - Jan 3) | 79.4% | -1.0 pts | 2.2% | 134 |
| Summer peak (Jun 15 - Aug 15) | 72.7% | -7.8 pts | 1.8% | 598 |
| All other days | 80.4% | — | 1.5% | 2,399 |
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).