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Route on-time record

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

Baltimore (Baltimore/Washington International Thurgood Marshall Airport) to Portland (Portland International Jetport). 1,342 nonstop flights in Jun 2025 to May 2026, 78% arrived within 15 minutes and 1.3% were cancelled. The most reliable flight number was Southwest 1275 at 2:45 PM.

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

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BWI → PWM

Baltimore to Portland: 1,342 nonstop flights a year

On time (12 months)

78%

Cancelled

1.3%

avg delay 12 min

Best time to leave

Before 9 AM

94% on time vs 60% after 9 PM

Most reliable airline

Southwest

77% chance on time

Check BWI to PWM fares

Lowest nonstop fare seen in the next two months: $368 (Southwest 4503 on 2026-10-29). 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 1275

    2:45 PM → 4:15 PM1h 30m nonstop

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

    86%

    chance on time

    On time (history)
    94%
    Cancelled
    0.0%
    Avg arrival delay
    4 min
    • Arrived on time 94% of the time (31 flights, Jun 2025 to May 2026).
    • Never cancelled in 31 scheduled flights.
    • Departs inside BWI's trouble window: 81% of its 43 ground stops and delay programs started between 2 PM and 8 PM.

    Limited track record · 31 flights

    Find Southwest 1275 fares Opens this date on Aviasales

  2. #2 · Southwest 2365

    10:40 AM → 12:10 PM1h 30m nonstop

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

    82%

    chance on time

    On time (history)
    80%
    Cancelled
    0.0%
    Avg arrival delay
    7 min
    • Arrived on time 80% of the time (55 flights, Jun 2025 to May 2026).
    • Never cancelled in 55 scheduled flights.
    • Departs outside BWI's trouble window (2 PM to 8 PM, when 81% of its 43 ground stops and delay programs started).

    Limited track record · 55 flights

    Find Southwest 2365 fares Opens this date on Aviasales

  3. #3 · Southwest 1274

    12:40 PM → 2:10 PM1h 30m nonstop

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

    79%

    chance on time

    On time (history)
    83%
    Cancelled
    0.0%
    Avg arrival delay
    6 min
    • Arrived on time 83% of the time (23 flights, Jun 2025 to May 2026).
    • Departs outside BWI's trouble window (2 PM to 8 PM, when 81% of its 43 ground stops and delay programs started).

    Limited track record · 23 flights

    Find Southwest 1274 fares Opens this date on Aviasales

  4. #4 · Southwest 2699

    1:50 PM → 3:20 PM1h 30m nonstop

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

    70%

    chance on time

    On time (history)
    57%
    Cancelled
    0.0%
    Avg arrival delay
    12 min
    • Arrived on time 57% of the time (23 flights, Jun 2025 to May 2026).
    • Departs outside BWI's trouble window (2 PM to 8 PM, when 81% of its 43 ground stops and delay programs started).
    • 56% of its delay minutes came from the plane arriving late from an earlier flight.

    Limited track record · 23 flights

    Find Southwest 2699 fares Opens this date on Aviasales

  5. #5 · Southwest 2484

    9:50 PM → 11:25 PM1h 35m nonstop

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

    70%

    chance on time

    On time (history)
    67%
    Cancelled
    0.0%
    Avg arrival delay
    15 min
    • Arrived on time 67% 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 (After 9 PM: 60% on time; Before 9 AM: 94%).
    • Departs outside BWI's trouble window (2 PM to 8 PM, when 81% of its 43 ground stops and delay programs started).

    Limited track record · 55 flights

    Find Southwest 2484 fares Opens this date on Aviasales

Airlines on this route

Season-adjusted chance of operating and arriving on time.

  • Southwest Airlines77%

    1,342 flights · 78% on time as flown · 1.3% cancel

On time by departure time

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

  • Before 9 AM94%

    104 flights · avg delay 3 min

  • 9 AM to noon90%

    318 flights · avg delay 5 min

  • Noon to 3 PM79%

    330 flights · avg delay 12 min

  • 3 to 6 PM68%

    178 flights · avg delay 19 min

  • 6 to 9 PM82%

    143 flights · avg delay 10 min

  • After 9 PM60%

    269 flights · avg delay 21 min

Best day: Wednesday (81%). Worst: Sunday (68%).

Smarter routing

Nearby airports that run more on time

  • IAD → PWM 84% chance on time

    Washington Dulles International Airport to Portland International Jetport · 821 flights a year · 45 mi from your airports · yours: 77%

    Rank flightsFares

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
80
F
87
M
79
A
78
M
71
J
68
J
60
A
72
S
79
O
83
N
82
D
73

What delays this route

  • Late-arriving aircraft51%
  • Airline (crew, maintenance, boarding)31%
  • Air traffic control and airport volume11%
  • Severe weather7%

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 BWI to PWM…

BWI to PWM questions

What time of day is best to fly BWI to PWM?
Before 9 AM: 94% of flights arrived on time, against 60% for departures after 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 BWI to PWM?
Southwest, with a season-adjusted 77% chance of operating and arriving on time over 1,342 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 BWI to PWM?
July (60% on time); the best was February (87%), 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 BWI

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Live status: FAA delays and ground stops