Baltimore, MD · departure reliability
BWI
Baltimore/Washington International Thurgood Marshall
- Departures
- 94,023
- Period
- September 2025 to August 2026
- Carriers
- 9
- US rank
- #25 by volume
Baltimore
Baltimore/Washington International Thurgood Marshall lands a B, level with the national rate of 77.3%. Roughly one flight in four arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 94,023 flights, of which Delta Air Lines flew 5,297 at 85.3% on time.
Delta Air Lines is the most reliable of the nine carriers covered here at 85.3% on time across 5,297 flights.
Key figures
On time
77.1%
Departures arriving under 15 minutes late at their destination
Avg delay
61 min
Across delayed flights only
Cancelled
1.95%
National rate is 1.89%
Best carrier
Delta
85.3% on time here
These figures cover 94,000 flights between September 2025 and August 2026. The median arrival is 5 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
Carrier by carrier
Which airlines run best out of BWI
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 85.3% of the time; Frontier Airlines manages 68.1%. Sample sizes sit next to every figure, because a two-point gap across 3,640 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Southwest Airlines | 71,953 | 76.5% | 55 min | 1.80% | B |
| Delta Air Lines | 5,297 | 85.3% | 90 min | 1.98% | A |
| United Airlines | 4,172 | 80.1% | 72 min | 0.93% | B+ |
| Frontier Airlines | 3,640 | 68.1% | 88 min | 4.04% | C− |
| American Airlines | 3,473 | 80.5% | 104 min | 2.10% | B |
| Spirit Airlines | 2,160 | 78.6% | 74 min | 3.29% | B− |
| Republic Airways | 1,435 | 81.1% | 88 min | 4.25% | B− |
| Envoy Air | 966 | 76.8% | 82 min | 3.31% | B− |
| Alaska Airlines | 710 | 69.2% | 52 min | 0.85% | C+ |
Republic Airways cancels 4.3% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.
Route by route
Busiest routes out of BWI
Route-level records vary far more than the airport average. These are the 25 busiest departures from BWI, each with its own on-time rate against the airport-wide 77.1%.
| Route | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| BWI to ATL · Atlanta | 5,405 | 79.9% | 70 min | 2.33% | B |
| BWI to MCO · Orlando | 4,707 | 75.5% | 69 min | 2.61% | B |
| BWI to BOS · Boston | 3,540 | 74.1% | 67 min | 3.16% | C− |
| BWI to FLL · Fort Lauderdale | 3,168 | 74.5% | 62 min | 2.71% | C |
| BWI to CLT · Charlotte | 2,948 | 80.8% | 76 min | 1.76% | B |
| BWI to DEN · Denver | 2,784 | 76.0% | 52 min | 1.40% | B |
| BWI to ORD · Chicago | 2,677 | 75.5% | 94 min | 2.54% | B |
| BWI to TPA · Tampa | 2,651 | 78.1% | 62 min | 2.04% | B |
| BWI to MIA · Miami | 2,294 | 75.3% | 73 min | 2.44% | B |
| BWI to DTW · Detroit | 2,233 | 80.8% | 76 min | 2.06% | B |
| BWI to PVD · Providence | 1,846 | 79.6% | 50 min | 2.28% | B |
| BWI to MDW · Chicago | 1,824 | 75.1% | 60 min | 2.36% | B |
| BWI to DAL · Dallas | 1,794 | 75.8% | 53 min | 2.06% | B |
| BWI to BNA · Nashville | 1,789 | 79.3% | 55 min | 1.84% | B |
| BWI to RDU · Raleigh | 1,765 | 80.7% | 60 min | 2.61% | B |
| BWI to ALB · Albany | 1,740 | 80.4% | 53 min | 1.78% | B |
| BWI to LAS · Las Vegas | 1,739 | 79.0% | 54 min | 0.92% | B+ |
| BWI to BUF · Buffalo | 1,727 | 75.9% | 52 min | 2.14% | B |
| BWI to BDL · Hartford | 1,723 | 81.2% | 55 min | 2.21% | B |
| BWI to MHT · Manchester | 1,721 | 84.2% | 60 min | 1.39% | B |
| BWI to LAX · Los Angeles | 1,670 | 72.8% | 56 min | 1.32% | C |
| BWI to ORF · Norfolk | 1,539 | 78.5% | 50 min | 1.62% | B |
| BWI to HOU · Houston | 1,471 | 75.7% | 55 min | 1.43% | B |
| BWI to MSP · Minneapolis | 1,423 | 78.5% | 80 min | 2.11% | B |
| BWI to RSW · Fort Myers | 1,407 | 74.7% | 54 min | 1.99% | C |
Departure window
The best time of day to leave BWI
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 25 points, against 17 points between the best and worst carrier.
- 5am–8am12,833 flights89.8%
- 8am–11am21,010 flights87.1%
- 11am–2pm13,501 flights80.0%
- 2pm–5pm15,334 flights72.9%
- 5pm–8pm17,269 flights66.3%
- 8pm–5am14,076 flights64.9%
Scale runs 55% to 95%.
The 8pm–5am window is where this operation falls apart: 64.9% on time, against 89.8% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 8am–11am window is the busiest, with 21,010 flights scheduled in it.
Explore
Filter BWI departures by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On departures from Baltimore (BWI), the best departure window is 5am–8am at 89.8% on time and the worst is 8pm–5am at 64.9%, a wide gap of 24.9 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am89.8%
- 8–11am87.1%
- 11am–2pm80.0%
- 2–5pm72.9%
- 5–8pm66.3%
- 8pm–5am64.9%
best all US flightsScale 55% to 95%.
Across the year
When BWI runs late
BWI's year swings by 17 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
August is the worst month at 68.9% on time, 17 points below September, the best at 85.5%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. July was the busiest month here, with 8,485 flights.
Across the week, Tuesday is the strongest day at 81.7% on time and Sunday the weakest at 71.3%, a spread of 10 points.
BWI month by month
From Europe
Transatlantic routes into BWI
2 European airports send scheduled passenger flights to BWI, 1,426 flights a year in both directions by the DOT's international count. The DOT keeps no delay record for international flights; the UK routes carry the CAA's departure punctuality, and every route sets its departure airport's EUROCONTROL figures beside BWI's own record above.
Delay causes
Why BWI gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 1.29 million reported delay minutes.
- 40%Late-arriving aircraft
- 33%Carrier
- 21%National Airspace System
- 5%Extreme weather
- 1%Security
40% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 1.29 million reported delay minutes here, that single category outweighs weather by 8 to one. The split is drawn from 1,287,398 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 89.8% on time here.
Cancellations sit at 1.95% against a national 1.89%, which is ordinary. Diversions add another 0.21%.
6.9% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
94,023 flights sit behind these numbers, which is a large enough sample that the headline rate is not moving on noise. Where a sub-group falls below 30 flights the site shows a dash instead of a percentage.
What to do with this
Flying out of BWI
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 85.5% on time and August 68.9%, a swing of 17 points. If the dates move at all, move them out of August before you think about anything else. 91,987 completed flights over 12 months sit behind that.
Common questions
BWI delay questions
How often is Baltimore (BWI) delayed?
Roughly one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 22.9% of the 94,023 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on Baltimore (BWI)?
Delta Air Lines leads at 85.3% on time across 5,297 flights. Frontier Airlines is at the other end on 68.1%, a gap of 17 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on Baltimore (BWI)?
The 5am–8am departure window is the strongest at 89.8% on time. The 8pm–5am window is the weakest at 64.9%, 25 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are August delays on Baltimore (BWI)?
August is the weakest month at 68.9% on time, compared with 85.5% in September. Across the year that is 17 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- BWI to ATL — Atlanta79.9%
- BWI to MCO — Orlando75.5%
- BWI to BOS — Boston74.1%
- BWI to FLL — Fort Lauderdale74.5%
- BWI to CLT — Charlotte80.8%
- BWI to DEN — Denver76.0%
- Southwest Airlines on-time record76.5%
- Delta Air Lines on-time record85.3%
- United Airlines on-time record80.1%
- Frontier Airlines on-time record68.1%
- Why the first flight of the morning is statistically safest
- US airports with the biggest gap between their best and worst month
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.