Best Time to Fly ATL to STL: On-Time Stats by Hour & Airline
Hartsfield-Jackson Atlanta International → St Louis Lambert International
Data through July 2026 · Last updated October 18, 2026
Over the last 12 months, 82.0% of Atlanta (ATL) to St. Louis (STL) flights arrived on time (3,685 scheduled flights). That is 4.4 points above the national average of 77.6%.
Among 3 airlines, Delta Air Lines led with 84.6% on time and Frontier Airlines was last with 68.0%.
Over 24 months, Tuesday was the most reliable day (88% on time) and July the worst month (76%).
The cancellation rate was 1.5% (US average 1.8%).
ATL 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 |
|---|---|---|---|---|
| Delta Air Lines | 84.6% | 57 min | 2.0% | 2,357 |
| Southwest Airlines | 79.5% | 57 min | 0.4% | 1,105 |
| Frontier Airlines | 68.0% | 52 min | 1.8% | 223 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly ATL to STL
On-time arrival % by scheduled departure hour (local time), 7,161 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 6am–7am | 93.7% | 0.8% | 127 |
| 7am–8am | 92.1% | 1.4% | 359 |
| 8am–9am | 89.4% | 1.4% | 903 |
| 9am–10am | 88.9% | 1.2% | 421 |
| 10am–11am | 88.5% | 3.5% | 171 |
| 11am–12pm | 89.2% | 1.0% | 678 |
| 12pm–1pm | 79.1% | 0.0% | 196 |
| 1pm–2pm | 84.4% | 1.6% | 378 |
| 2pm–3pm | 83.2% | 0.5% | 557 |
| 3pm–4pm | 83.8% | 0.8% | 636 |
| 4pm–5pm | 68.3% | 2.7% | 149 |
| 5pm–6pm | 75.0% | 1.8% | 543 |
| 6pm–7pm | 84.2% | 1.3% | 315 |
| 7pm–8pm | 71.5% | 0.5% | 374 |
| 8pm–9pm | 62.4% | 1.0% | 499 |
| 9pm–10pm | 76.7% | 1.0% | 199 |
| 10pm–11pm | 77.1% | 1.9% | 320 |
| 11pm–12am | 79.2% | 1.2% | 336 |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on ATL 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) | 71.8% | -11.7 pts | 0.7% | 136 |
| Christmas & New Year (Dec 20 - Jan 3) | 78.0% | -5.5 pts | 1.0% | 303 |
| Summer peak (Jun 15 - Aug 15) | 78.1% | -5.4 pts | 1.3% | 1,351 |
| All other days | 83.5% | — | 1.2% | 5,371 |
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).