Carrier route record
WNDEN→BWI
Southwest Airlines · Denver to Baltimore
- Flights
- 1,907
- Period
- July 2025 to June 2026
- Share of route
- 66%
- Carriers
- 3
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on DEN to BWI sits in the middle of the pack with a B. Close to three flights in four arrive on time by the DOT's definition, 3 points worse than the national rate of 77.6%. The late ones land roughly 50 minutes behind schedule. That rests on 1,907 flights, with a median arrival 3 minutes early.
The US average over the same twelve months is 77.6%, so there is little to separate Southwest on DEN to BWI from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
75.1%
Arrivals under 15 minutes late, of 1,870 completed flights
Avg delay
51 min
Across delayed arrivals only, not all flights
Cancelled
1.47%
National rate is 1.81%
Whole route
76.8%
Every carrier on DEN to BWI, 2,868 flights
These figures cover 1,907 flights between July 2025 and June 2026. The median arrival is 3 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
Southwest against every carrier on DEN to BWI
Southwest flew 1,907 of the 2,868 flights on DEN to BWI, most of the route. Its 75.1% on time is 2 points worse than the route as a whole, which runs 76.8%. Ranked by on-time rate it is number two of three carriers on the route, where the range runs from United at 80.6% to Frontier at 71.7%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 901 | 80.6% | 52 min | 0.78% | B+ |
| Southwest Airlines (this page) | 1,907 | 75.1% | 51 min | 1.47% | B |
| Frontier Airlinesthin sample | 60 | 71.7% | 83 min | 0.00% | C+ |
Departure window
When Southwest runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 51 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am465 flights93.7%
- 8am–11am275 flights83.8%
- 11am–2pm212 flights68.8%
- 2pm–5pm333 flights67.5%
- 5pm–8pm291 flights42.4%
- 8pm–5am331 flights82.0%
Scale runs 35% to 100%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 42.4% on time, against 93.7% 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 5am–8am window is the busiest, with 465 flights scheduled in it.
Across the year
Southwest on DEN to BWI through the year
July is the worst month at 60.1% on time, 25 points below January, the best at 85.0%. 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 208 flights.
Across the week, Wednesday is the strongest day at 79.2% on time and Monday the weakest at 71.5%. 8 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Southwest runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 53% of the 24,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 53%Late-arriving aircraft
- 31%Carrier
- 15%National Airspace System
- 1%Extreme weather
53% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 24,000 reported delay minutes here, that single category outweighs weather by 53 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 23,903 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 93.7% on time here.
Cancellations sit at 1.47% against a national 1.81%, which is ordinary. Diversions add another 0.47%.
Connections and stage length
What a delay here costs
6.6% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last roughly 50 minutes, which a normal layover absorbs.
The 1,491 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The return leg is a different operation and performs like one: it runs 71.7% on time across 1,905 flights, 3 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 3 points of difference.
The sample behind these figures is 1,907 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
What to do with this
Booking Southwest on DEN to BWI
Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 85.0% on time and July 60.1%, a swing of 25 points. If the dates move at all, move them out of July before you think about anything else. 1,870 completed flights over 12 months sit behind that.
Related
Where to go next
- DEN to BWI, every carrier
- Southwest on BWI to DEN, the return leg
- United Airlines on DEN to BWI80.6%
- Southwest Airlines network-wide record
- Denver International (DEN) delay statistics
- Baltimore/Washington International Thurgood Marshall (BWI) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.