Route on-time record
PWM to BWI: most on-time flights and the best time to fly
Portland (Portland International Jetport) to Baltimore (Baltimore/Washington International Thurgood Marshall Airport). 1,343 nonstop flights in Jun 2025 to May 2026, 81% arrived within 15 minutes and 0.9% were cancelled. The most reliable flight number was Southwest 3976 at 5:30 AM.
Flying on a specific date? We’ll adjust for the month, the weekday and the forecast.
PWM → BWI
Portland to Baltimore: 1,343 nonstop flights a year
On time (12 months)
81%
Cancelled
0.9%
avg delay 13 min
Best time to leave
Before 9 AM
90% on time vs 68% 3 to 6 PM
Most reliable airline
Southwest
80% chance on time
Lowest nonstop fare seen in the next two months: $218 (Southwest 3596 on 2026-11-24). 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 · Southwest 3976
5:30 AM → 7:15 AM1h 45m nonstop
Local times, typical schedule. Last flown 2026-05-31.
90%
chance on time
- On time (history)
- 93%
- Cancelled
- 0.0%
- Avg arrival delay
- 2 min
- Arrived on time 93% 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: 90% on time; 3 to 6 PM: 68%).
Limited track record · 55 flights
Find Southwest 3976 fares Opens this date on Aviasales#2 · Southwest 1317
12:45 PM → 2:25 PM1h 40m nonstop
Local times, typical schedule. Last flown 2026-05-31.
79%
chance on time
- On time (history)
- 78%
- Cancelled
- 0.0%
- Avg arrival delay
- 10 min
- Arrived on time 78% of the time (55 flights, Jun 2025 to May 2026).
- Never cancelled in 55 scheduled flights.
- Lands inside BWI's trouble window: 81% of its 43 ground stops and delay programs started between 2 PM and 8 PM.
Limited track record · 55 flights
Find Southwest 1317 fares Opens this date on Aviasales#3 · Southwest 3218
2:50 PM → 4:35 PM1h 45m nonstop
Local times, typical schedule. Last flown 2026-05-29.
78%
chance on time
- On time (history)
- 74%
- Cancelled
- 0.0%
- Avg arrival delay
- 19 min
- Arrived on time 74% 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.
Limited track record · 23 flights
Find Southwest 3218 fares Opens this date on Aviasales#4 · Southwest 1635
4:50 PM → 6:35 PM1h 45m nonstop
Local times, typical schedule. Last flown 2026-05-31.
71%
chance on time
- On time (history)
- 69%
- Cancelled
- 0.0%
- Avg arrival delay
- 15 min
- Arrived on time 69% 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 (3 to 6 PM: 68% on time; Before 9 AM: 90%).
- Lands inside BWI's trouble window: 81% of its 43 ground stops and delay programs started between 2 PM and 8 PM.
Limited track record · 55 flights
Find Southwest 1635 fares Opens this date on Aviasales
Airlines on this route
Season-adjusted chance of operating and arriving on time.
- Southwest Airlines80%
1,343 flights · 81% on time as flown · 0.9% cancel
On time by departure time
All airlines, scheduled local departure, Jun 2025 to May 2026.
- Before 9 AM90%
405 flights · avg delay 9 min
- 9 AM to noon89%
178 flights · avg delay 9 min
- Noon to 3 PM81%
368 flights · avg delay 11 min
- 3 to 6 PM68%
391 flights · avg delay 22 min
Best day: Wednesday (84%). Worst: Friday (78%).
Smarter routing
Nearby airports that run more on time
PWM → IAD 83% chance on time
Portland International Jetport to Washington Dulles International Airport · 701 flights a year · 45 mi from your airports · yours: 80%
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.
What delays this route
- Late-arriving aircraft39%
- Airline (crew, maintenance, boarding)30%
- Air traffic control and airport volume22%
- Severe weather8%
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
PWM to BWI questions
- What time of day is best to fly PWM to BWI?
- Before 9 AM: 90% of flights arrived on time, against 68% 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 PWM to BWI?
- Southwest, with a season-adjusted 80% chance of operating and arriving on time over 1,343 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 PWM to BWI?
- July (67% on time); the best was November (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.
More routes from PWM
- BWI to PWM (return)
- PWM to ORD 76%
- PWM to DCA 73%
- PWM to LGA 81%
- PWM to EWR 83%
- PWM to PHL 77%
- PWM to CLT 80%
- PWM to IAD 85%
- PWM to ATL 78%
- PWM to DTW 79%
- PWM to JFK 80%
Live status: FAA delays and ground stops