Carrier route record
WNBWI→DEN
Southwest Airlines · Baltimore to Denver
- Flights
- 1,905
- 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 BWI to DEN sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 6 points worse than the national rate of 77.6%. The late ones land roughly 55 minutes behind schedule. That rests on 1,905 flights, with a median arrival right on schedule.
The national on-time rate over the same period is 77.6%, so Southwest on BWI to DEN runs 6 points behind the country as a whole. Across a thousand flights that is about 59 extra late arrivals.
Key figures
On time
71.7%
Arrivals under 15 minutes late, of 1,870 completed flights
Avg delay
53 min
Across delayed arrivals only, not all flights
Cancelled
1.42%
National rate is 1.81%
Whole route
75.6%
Every carrier on BWI to DEN, 2,867 flights
These figures cover 1,905 flights between July 2025 and June 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.
Carrier by carrier
Southwest against every carrier on BWI to DEN
Southwest flew 1,905 of the 2,867 flights on BWI to DEN, most of the route. Its 71.7% on time is 4 points worse than the route as a whole, which runs 75.6%. Ranked by on-time rate it is number two of three carriers on the route, where the range runs from United at 85.6% to Frontier at 50.0%. 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 | 902 | 85.6% | 77 min | 0.55% | A+ |
| Southwest Airlines (this page) | 1,905 | 71.7% | 53 min | 1.42% | C |
| Frontier Airlinesthin sample | 60 | 50.0% | 87 min | 0.00% | F+ |
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 30 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–8am357 flights85.8%
- 8am–11am372 flights81.9%
- 11am–2pm233 flights73.4%
- 2pm–5pm372 flights64.2%
- 5pm–8pm404 flights62.5%
- 8pm–5am167 flights55.5%
Scale runs 45% to 90%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 55.5% on time, against 85.8% 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 5pm–8pm window is the busiest, with 404 flights scheduled in it.
Across the year
Southwest on BWI to DEN through the year
December is the weak month at 53.4% on time, against 87.2% in October. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. July was the busiest month here, with 208 flights.
Across the week, Tuesday is the strongest day at 77.7% on time and Friday the weakest at 67.7%. 10 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Southwest runs late on this route
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 28,000 reported delay minutes.
- 33%Carrier
- 31%National Airspace System
- 30%Late-arriving aircraft
- 4%Extreme weather
- 1%Security
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 85.8% on time here. The split is drawn from 28,160 reported delay minutes.
No single cause dominates. carrier at 33%, national airspace system at 31% and late-arriving aircraft at 30% split the 28,000 reported delay minutes between them. An even spread like this usually means the operation is running close to its designed capacity with no one obvious weak point, and it is the hardest pattern for a traveller to route around.
Cancellations sit at 1.42% against a national 1.81%, which is ordinary. Diversions add another 0.42%.
Connections and stage length
What a delay here costs
7.6% 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 55 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 75.1% on time across 1,907 flights, 3 points above 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 1,905 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 BWI to DEN
Put together: the calendar is the biggest lever here, not the carrier or the hour. October runs 87.2% on time and December 53.4%, a swing of 34 points. If the dates move at all, move them out of December before you think about anything else. 1,870 completed flights over 12 months sit behind that.
Related
Where to go next
- BWI to DEN, every carrier
- Southwest on DEN to BWI, the return leg
- United Airlines on BWI to DEN85.6%
- Southwest Airlines network-wide record
- Baltimore/Washington International Thurgood Marshall (BWI) delay statistics
- Denver International (DEN) delay statistics
- The best time of day to fly, according to 7.04 million flight records
- Worst months to fly in the US, ranked by the data
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.