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Route on-time record

BOS to STL: most on-time flights and the best time to fly

Boston (Boston Logan International Airport) to St Louis (St. Louis Lambert International Airport). 1,613 nonstop flights in Jun 2025 to May 2026, 76% arrived within 15 minutes and 1.4% were cancelled. The most reliable flight number was Southwest 900 at 5:40 AM.

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BOS → STL

Boston to St Louis: 1,613 nonstop flights a year

On time (12 months)

76%

Cancelled

1.4%

avg delay 16 min

Best time to leave

Before 9 AM

93% on time vs 43% 6 to 9 PM

Most reliable airline

Republic

81% chance on time

Check BOS to STL fares

Fares open on our travel partner (Aviasales). Pick the flight number you chose here.

Most reliable nonstop flights

Ranked by the chance the flight operates and arrives within 15 minutes of schedule, from Jun 2025 to May 2026 records.

  1. #1 · Southwest 900

    5:40 AM → 7:40 AM3h 00m nonstop

    Local times, typical schedule. Last flown 2026-05-31.

    90%

    chance on time

    On time (history)
    96%
    Cancelled
    0.0%
    Avg arrival delay
    1 min
    • Arrived on time 96% of the time (54 flights, Jun 2025 to May 2026).
    • Never cancelled in 54 scheduled flights.
    • Leaves in this route's most on-time window (Before 9 AM: 93% on time; 6 to 9 PM: 43%).
    • Departs outside BOS's trouble window (noon to 6 PM, when 79% of its 196 ground stops and delay programs started).

    Limited track record · 54 flights

    Find Southwest 900 fares Opens this date on Aviasales

  2. #2 · Republic 4518 · sold as American Eagle, Delta Connection or United Express

    8:41 AM → 10:54 AM3h 13m nonstop

    Local times, typical schedule. Last flown 2026-05-20.

    86%

    chance on time

    On time (history)
    90%
    Cancelled
    0.0%
    Avg arrival delay
    6 min
    • Arrived on time 90% of the time (42 flights, Jun 2025 to May 2026).
    • Never cancelled in 43 scheduled flights.
    • Leaves in this route's most on-time window (Before 9 AM: 93% on time; 6 to 9 PM: 43%).
    • Departs outside BOS's trouble window (noon to 6 PM, when 79% of its 196 ground stops and delay programs started).

    Limited track record · 42 flights

    Find 8:41 AM flight fares Opens this date on Aviasales

  3. #3 · Southwest 901

    11:35 AM → 1:30 PM2h 55m nonstop

    Local times, typical schedule. Last flown 2026-05-31.

    83%

    chance on time

    On time (history)
    89%
    Cancelled
    0.0%
    Avg arrival delay
    6 min
    • Arrived on time 89% of the time (37 flights, Jun 2025 to May 2026).
    • Never cancelled in 38 scheduled flights.
    • Departs outside BOS's trouble window (noon to 6 PM, when 79% of its 196 ground stops and delay programs started).

    Limited track record · 37 flights

    Find Southwest 901 fares Opens this date on Aviasales

  4. #4 · Envoy 4224 · sold as American Eagle

    3:00 PM → 5:12 PM3h 12m nonstop

    Local times, typical schedule. Last flown 2026-05-20.

    77%

    chance on time

    On time (history)
    81%
    Cancelled
    0.0%
    Avg arrival delay
    19 min
    • Arrived on time 81% of the time (43 flights, Jun 2025 to May 2026).
    • Never cancelled in 43 scheduled flights.
    • Departs inside BOS's trouble window: 79% of its 196 ground stops and delay programs started between noon and 6 PM.
    • 85% of its delay minutes came from the plane arriving late from an earlier flight.

    Limited track record · 43 flights

    Find 3:00 PM flight fares Opens this date on Aviasales

  5. #5 · Republic 4678 · sold as American Eagle, Delta Connection or United Express

    5:11 PM → 7:21 PM3h 10m nonstop

    Local times, typical schedule. Last flown 2026-05-31.

    70%

    chance on time

    On time (history)
    55%
    Cancelled
    0.0%
    Avg arrival delay
    22 min
    • Arrived on time 55% of the time (11 flights, Jun 2025 to May 2026).
    • Departs inside BOS's trouble window: 79% of its 196 ground stops and delay programs started between noon and 6 PM.
    • 67% of its delay minutes came from the plane arriving late from an earlier flight.

    Limited track record · 11 flights

    Find 5:11 PM flight fares Opens this date on Aviasales

  6. #6 · Southwest 908

    6:45 PM → 8:55 PM3h 05m nonstop

    Local times, typical schedule. Last flown 2026-05-31.

    53%

    chance on time

    On time (history)
    56%
    Cancelled
    0.0%
    Avg arrival delay
    30 min
    • Arrived on time 56% of the time (55 flights, Jun 2025 to May 2026).
    • Never cancelled in 55 scheduled flights.
    • Leaves in this route's least on-time window (6 to 9 PM: 43% on time; Before 9 AM: 93%).
    • Departs outside BOS's trouble window (noon to 6 PM, when 79% of its 196 ground stops and delay programs started).

    Limited track record · 55 flights

    Find Southwest 908 fares Opens this date on Aviasales

Airlines on this route

Season-adjusted chance of operating and arriving on time.

  • Republic Airways (sold as American Eagle, Delta Connection or United Express)81%

    228 flights · 85% on time as flown · 2.4% cancel

  • Envoy Air (sold as American Eagle)79%

    448 flights · 80% on time as flown · 1.4% cancel

  • Southwest Airlines72%

    937 flights · 72% on time as flown · 1.1% cancel

On time by departure time

All airlines, scheduled local departure, Jun 2025 to May 2026.

  • Before 9 AM93%

    655 flights · avg delay 5 min

  • 9 AM to noon86%

    190 flights · avg delay 8 min

  • Noon to 3 PM71%

    206 flights · avg delay 14 min

  • 3 to 6 PM64%

    335 flights · avg delay 27 min

  • 6 to 9 PM43%

    227 flights · avg delay 40 min

Best day: Saturday (84%). Worst: Sunday (76%).

On time by month

All airlines, Jun 2023 to May 2026. Several years per month, so one stormy season doesn't define a month. Travel-month estimates use this seasonal pattern.

J
84
F
89
M
82
A
84
M
80
J
74
J
69
A
78
S
77
O
77
N
87
D
82

What delays this route

  • Late-arriving aircraft63%
  • Airline (crew, maintenance, boarding)24%
  • Air traffic control and airport volume10%
  • Severe weather3%

Share of delay minutes by the cause airlines report to the US DOT.

Historical odds, not a guarantee. Built from the US DOT Bureau of Transportation Statistics on-time reports (Jun 2025 to May 2026), FAA ground stop and delay program advisories, and 20 years of airport weather observations. Covers US airlines that report to the DOT; schedules are flights operated recently, so confirm times when you book. ATIS Alerts is not affiliated with any airline. Fares are what Aviasales travelers saw in recent searches (USD, one way, 1 adult), not live quotes; the partner site shows the current price. Fare links go to our travel partner and may earn us a commission at no cost to you. Affiliate disclosure

Finding the most reliable connections from BOS to STL…

BOS to STL questions

What time of day is best to fly BOS to STL?
Before 9 AM: 93% of flights arrived on time, against 43% for departures 6 to 9 PM. Later flights inherit delays from earlier ones, so the first departures of the day usually run best.
Which airline is most on time from BOS to STL?
Republic, with a season-adjusted 81% chance of operating and arriving on time over 228 flights. The adjustment compares each airline with what the route did in the months it flew, so a carrier that skipped a stormy month gets no free credit.
What is the worst month for delays on BOS to STL?
July (69% on time); the best was February (89%), averaged over Jun 2023 to May 2026.
Is this a prediction for my flight?
No. These are historical odds from the US DOT on-time reports, FAA advisories and airport weather records. Check your flight status and the FAA delay board on the day you fly.

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