Best time to fly out of Baltimore (BWI)

The early-flight folk wisdom holds up at Baltimore/Washington Thurgood Marshall: departures in the Before 6am band left on time 92.7% of the time, against 43.9% in the 10pm–12am band. These are historical odds, not forecasts. The records say what happened on this schedule over three years; they know nothing about tomorrow’s thunderstorm.

Data through June 2026 · Bureau of Transportation Statistics

On-time rate by hour and day

On this page, “on time” means a departure that pushed back less than 15 minutes behind its scheduled time — the Bureau of Transportation Statistics definition, and the one airlines are held to.

Share of departures that left on time, by hour band and day of week.
Departure time MonTueWedThuFriSatSun
Before 6am 93 95 92 95 94 89 91
6–8am 90 92 92 92 89 89 90
8–10am 83 87 88 86 84 83 84
10am–12pm 80 84 85 82 81 81 80
12–2pm 73 79 81 74 73 75 71
2–4pm 65 68 69 64 64 66 63
4–6pm 63 71 69 64 63 64 59
6–8pm 62 68 64 59 59 58 55
8–10pm 56 62 62 53 54 51 48
10pm–12am 46 47 51 47 48 36 38
fewer left on time more left on time

The steadiest stretch at BWI was Before 6am — 92.7% of departures left on time across 2,426 flights. The weakest was 10pm–12am at 43.9%. 6–8am departures from BWI left on time 90.5% of the time across 38,484 flights; 6–8pm departures, 60.9% across 36,089. That is a gap of 29.6 points, and it is the whole case for the early flight.

The year at BWI

July was the hard month at BWI: 57.9% of departures left on time, across 26,462 flights. November was the easy one at 80.7%. Each month pools three years of that month, so a single bad week does not decide it.

Share of departures that left on time, by calendar month. Best month in green, worst in amber. The hairline sits at the overall rate, 72.2%.
Departure on-time share at BWI by calendar month
Month Share departures that left on time Flights
January 76.3% 21,579
February 80% 20,017
March 71% 23,806
April 75.9% 24,378
May 69% 25,226
June 65.1% 25,484
July 57.9% 26,462
August 68% 25,828
September 78.9% 24,253
October 77.2% 25,661
November 80.7% 23,810
December 70.3% 24,189

Airlines at BWI

Every airline with at least 100 departures from BWI, busiest first. These are that airline’s departures from this airport only — its record across the country sits on its own page.

Airline Left on time Typical delay Cancelled Departures
Southwest Airlines 69.7% 50 min 1.2% 218,264
Spirit Airlines 76.5% 76 min 1.9% 15,908
Delta Air Lines 84.3% 81 min 1.1% 15,756
United Airlines 86.7% 79 min 1.3% 11,522
American Airlines 80.1% 99 min 2% 10,895
Frontier Airlines 69.5% 97 min 3% 9,032
Republic Airways 83.6% 87 min 2.3% 3,333
Envoy Air 80.8% 73 min 2.3% 2,243
Alaska Airlines 71.1% 48 min 1.3% 1,747
Endeavor Air 83.2% 111 min 5.4% 930
JetBlue Airways 78.9% 101 min 2.4% 579
Allegiant Air 71.7% 94 min 0.9% 232
PSA Airlines 77.5% 57 min 1.8% 163

What delays out of BWI were put down to

Airlines file a reason with every arrival running 15 minutes late or more. Across 68,310 flights that departed BWI and ran 15 minutes late or more, the delay minutes break down with 39.9% put down to late-arriving aircraft and 34.7% to airline operations.

Late-arriving aircraft 39.9% Airline operations 34.7% Air traffic & airport volume 20.8% Severe weather 4.2% Security 0.3%
  • Late-arriving aircraft 39.9%
  • Airline operations 34.7%
  • Air traffic & airport volume 20.8%
  • Severe weather 4.2%
  • Security 0.3%

Late-arriving aircraft is the knock-on category: the plane came in late, so it went out late again. It is why a 7am problem in Newark is still a problem in Denver at dinnertime, and why it is usually the biggest slice on the bar.

If you are connecting through BWI

Of 290,691 scheduled arrivals into BWI, 79% reached the gate less than 15 minutes behind schedule. Of the 56,574 arrivals that ran late, 59.8% were no more than 45 minutes behind — which is the difference between a tight connection and a new boarding pass.

Work out a specific layover — pick the airport and the minutes you have, and the tool reads the same arrival records back as a share.

Busiest routes out of BWI

Ranked by flights, with the share that arrived on time at the far end. Where a route carries enough flights for a page of its own the chip goes there; otherwise it goes to the destination airport.

BWI in one number

Baltimore/Washington Thurgood Marshall (BWI)

Rank 24 of 363 US airports by departures. Steadiest stretch of the day: Before 6am. Hardest month: July.

July 2023–June 2026 · 286,800 departures flown

72.2% of departures left on time

Questions about BWI

What is the best time of day to fly out of Baltimore/Washington Thurgood Marshall?
Before 6am. Departures in that band left on time 92.7% of the time across 2,426 flights, July 2023 through June 2026 — the best of the ten bands in the day. The 10pm–12am band was the weakest at 43.9%.
Is the early flight out of BWI really more reliable?
6–8am departures from BWI left on time 90.5% of the time across 38,484 flights; 6–8pm departures, 60.9% across 36,089. That is a gap of 29.6 points, and it is the whole case for the early flight.
What is the worst month to fly out of BWI?
July: 57.9% of the departures that flew left on time, with 26,462 scheduled. November was the other end of the year at 80.7%. Each figure pools three years of that calendar month.
Which airline is most on time at BWI?
United Airlines — 86.7% of its 11,522 departures from BWI left on time. Frontier Airlines sat at the other end at 69.5% over 9,032 flights. Only airlines with at least 100 departures here are ranked.
How often are flights cancelled at BWI?
1.3% of scheduled departures were cancelled over July 2023 through June 2026. Cancellations are counted against everything scheduled, not against everything that flew — a rate that looks small still adds up to real people in a rebooking line.