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Route on-time record

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

St Louis (St. Louis Lambert International Airport) to Baltimore (Baltimore/Washington International Thurgood Marshall Airport). 1,288 nonstop flights in Jun 2025 to May 2026, 81% arrived within 15 minutes and 1.2% were cancelled. The most reliable flight number was Southwest 4440 at 5:00 AM.

Flying on a specific date? We’ll adjust for the month, the weekday and the forecast.

STL → BWI

St Louis to Baltimore: 1,288 nonstop flights a year

On time (12 months)

81%

Cancelled

1.2%

avg delay 13 min

Best time to leave

Before 9 AM

96% on time vs 65% 3 to 6 PM

Most reliable airline

Southwest

80% chance on time

Check STL to BWI fares

Lowest nonstop fare seen in the next two months: $597 (Southwest 1057 on 2026-10-21). 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 4440

    5:00 AM → 8:05 AM2h 05m nonstop

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

    93%

    chance on time

    On time (history)
    96%
    Cancelled
    0.0%
    Avg arrival delay
    1 min
    • Arrived on time 96% of the time (55 flights, Jun 2025 to May 2026).
    • Never cancelled in 55 scheduled flights.
    • Leaves in this route's most on-time window (Before 9 AM: 96% on time; 3 to 6 PM: 65%).
    • Short track record (55 flights), so its score leans on the airline's record at this hour.

    Limited track record · 55 flights

    Find Southwest 4440 fares Opens this date on Aviasales

  2. #2 · Southwest 4131

    6:15 AM → 9:15 AM2h 00m nonstop

    Local times, typical schedule. Last flown 2026-04-05.

    91%

    chance on time

    On time (history)
    100%
    Cancelled
    0.0%
    Avg arrival delay
    0 min
    • Arrived on time 100% of the time (13 flights, Jun 2025 to May 2026).
    • Leaves in this route's most on-time window (Before 9 AM: 96% on time; 3 to 6 PM: 65%).
    • Short track record (13 flights), so its score leans on the airline's record at this hour.

    Limited track record · 13 flights

    Find Southwest 4131 fares Opens this date on Aviasales

  3. #3 · Southwest 2741

    5:20 AM → 8:20 AM2h 00m nonstop

    Local times, typical schedule. Last flown 2026-04-06.

    89%

    chance on time

    On time (history)
    88%
    Cancelled
    0.0%
    Avg arrival delay
    5 min
    • Arrived on time 88% of the time (25 flights, Jun 2025 to May 2026).
    • Leaves in this route's most on-time window (Before 9 AM: 96% on time; 3 to 6 PM: 65%).
    • Short track record (25 flights), so its score leans on the airline's record at this hour.

    Limited track record · 25 flights

    Find Southwest 2741 fares Opens this date on Aviasales

  4. #4 · Southwest 2098

    11:15 AM → 2:15 PM2h 00m nonstop

    Local times, typical schedule. Last flown 2026-05-29.

    88%

    chance on time

    On time (history)
    96%
    Cancelled
    0.0%
    Avg arrival delay
    4 min
    • Arrived on time 96% of the time (23 flights, Jun 2025 to May 2026).
    • Lands inside BWI's trouble window: 81% of its 43 ground stops and delay programs started between 2 PM and 8 PM.
    • Short track record (23 flights), so its score leans on the airline's record at this hour.

    Limited track record · 23 flights

    Find Southwest 2098 fares Opens this date on Aviasales

  5. #5 · Southwest 2737

    1:15 PM → 4:20 PM2h 05m nonstop

    Local times, typical schedule. Last flown 2026-05-30.

    87%

    chance on time

    On time (history)
    100%
    Cancelled
    0.0%
    Avg arrival delay
    0 min
    • Arrived on time 100% of the time (24 flights, Jun 2025 to May 2026).
    • Lands inside BWI's trouble window: 81% of its 43 ground stops and delay programs started between 2 PM and 8 PM.
    • Short track record (24 flights), so its score leans on the airline's record at this hour.

    Limited track record · 24 flights

    Find Southwest 2737 fares Opens this date on Aviasales

  6. #6 · Southwest 2390

    1:40 PM → 4:40 PM2h 00m nonstop

    Local times, typical schedule. Last flown 2026-04-06.

    82%

    chance on time

    On time (history)
    86%
    Cancelled
    6.7%
    Avg arrival delay
    5 min
    • Arrived on time 86% of the time (14 flights, Jun 2025 to May 2026).
    • Lands inside BWI's trouble window: 81% of its 43 ground stops and delay programs started between 2 PM and 8 PM.
    • Short track record (14 flights), so its score leans on the airline's record at this hour.

    Limited track record · 14 flights

    Find Southwest 2390 fares Opens this date on Aviasales

  7. #7 · Southwest 2523

    4:45 PM → 7:40 PM1h 55m nonstop

    Local times, typical schedule. Last flown 2026-04-06.

    75%

    chance on time

    On time (history)
    73%
    Cancelled
    3.6%
    Avg arrival delay
    20 min
    • Arrived on time 73% of the time (26 flights, Jun 2025 to May 2026).
    • Leaves in this route's least on-time window (3 to 6 PM: 65% on time; Before 9 AM: 96%).
    • Lands inside BWI's trouble window: 81% of its 43 ground stops and delay programs started between 2 PM and 8 PM.
    • Short track record (26 flights), so its score leans on the airline's record at this hour.

    Limited track record · 26 flights

    Find Southwest 2523 fares Opens this date on Aviasales

  8. #8 · Southwest 3144

    4:00 PM → 7:05 PM2h 05m nonstop

    Local times, typical schedule. Last flown 2026-05-29.

    73%

    chance on time

    On time (history)
    74%
    Cancelled
    0.0%
    Avg arrival delay
    13 min
    • Arrived on time 74% of the time (23 flights, Jun 2025 to May 2026).
    • Leaves in this route's least on-time window (3 to 6 PM: 65% on time; Before 9 AM: 96%).
    • Lands inside BWI's trouble window: 81% of its 43 ground stops and delay programs started between 2 PM and 8 PM.
    • 75% of its delay minutes came from the plane arriving late from an earlier flight.

    Limited track record · 23 flights

    Find Southwest 3144 fares Opens this date on Aviasales

  9. #9 · Southwest 4442

    7:45 PM → 10:45 PM2h 00m nonstop

    Local times, typical schedule. Last flown 2026-05-31. Same departure also flew as Southwest 4633; its record covers all of them.

    68%

    chance on time

    On time (history)
    67%
    Cancelled
    0.0%
    Avg arrival delay
    27 min
    • Arrived on time 67% of the time (88 flights, Jun 2025 to May 2026).
    • Never cancelled in 88 scheduled flights.
    • 58% of its delay minutes came from the plane arriving late from an earlier flight.

    Moderate track record · 88 flights

    Find Southwest 4442 fares Opens this date on Aviasales

Airlines on this route

Season-adjusted chance of operating and arriving on time.

  • Southwest Airlines80%

    1,288 flights · 81% on time as flown · 1.2% cancel

On time by departure time

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

  • Before 9 AM96%

    427 flights · avg delay 3 min

  • 9 AM to noon92%

    189 flights · avg delay 7 min

  • Noon to 3 PM79%

    172 flights · avg delay 13 min

  • 3 to 6 PM65%

    194 flights · avg delay 22 min

  • 6 to 9 PM66%

    292 flights · avg delay 24 min

Best day: Tuesday (86%). Worst: Sunday (79%).

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
88
F
90
M
79
A
83
M
80
J
78
J
67
A
82
S
85
O
86
N
85
D
80

What delays this route

  • Late-arriving aircraft60%
  • Airline (crew, maintenance, boarding)23%
  • Air traffic control and airport volume12%
  • Severe weather5%

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

STL to BWI questions

What time of day is best to fly STL to BWI?
Before 9 AM: 96% of flights arrived on time, against 65% for departures 3 to 6 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 STL to BWI?
Southwest, with a season-adjusted 80% chance of operating and arriving on time over 1,288 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 STL to BWI?
July (67% on time); the best was February (90%), 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.

More routes from STL

Live status: FAA delays and ground stops