Carrier route record
WNBWI→DEN
Southwest Airlines · Baltimore to Denver
- Flights
- 1,919
- Period
- September 2025 to August 2026
- Share of route
- 69%
- Carriers
- 3
Historical statistics for September 2025 to August 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, 5 points worse than the national rate of 77.3%. The late ones land about 50 minutes behind schedule. That rests on 1,919 flights, with a median arrival right on schedule.
The national on-time rate over the same period is 77.3%, so Southwest on BWI to DEN runs 5 points behind the country as a whole. Across a thousand flights that is about 51 extra late arrivals.
Key figures
On time
72.2%
Arrivals under 15 minutes late, of 1,872 completed flights
Avg delay
50 min
Across delayed arrivals only, not all flights
Cancelled
1.82%
National rate is 1.89%
Whole route
76.0%
Every carrier on BWI to DEN, 2,784 flights
These figures cover 1,919 flights between September 2025 and August 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.
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Carrier by carrier
Southwest against every carrier on BWI to DEN
Southwest flew 1,919 of the 2,784 flights on BWI to DEN, most of the route. Its 72.2% on time is 4 points worse than the route as a whole, which runs 76.0%. Ranked by on-time rate it is number two of three carriers on the route, where the range runs from United at 84.5% to Frontier at 72.0%. 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 | 840 | 84.5% | 61 min | 0.48% | B+ |
| Southwest Airlines (this page) | 1,919 | 72.2% | 50 min | 1.82% | C |
| Frontier Airlinesthin sample | 25 | 72.0% | 51 min | 0.00% | C+ |
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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 23 points, against half a point between the best and worst carrier.
- 5am–8am362 flights85.1%
- 8am–11am382 flights82.2%
- 11am–2pm263 flights69.4%
- 2pm–5pm380 flights64.1%
- 5pm–8pm380 flights64.0%
- 8pm–5am152 flights61.6%
Scale runs 55% to 90%.
The 8pm–5am window is where this operation falls apart: 61.6% on time, against 85.1% 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 382 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 203 flights.
Across the week, Tuesday is the strongest day at 75.9% on time and Wednesday the weakest at 67.3%, a spread of 9 points.
Arrival by arrival
How late Southwest on BWI to DEN runs when it is late
The 520 late arrivals split 226 under half an hour, 160 between 30 and 60 minutes, and 134 an hour or more.
- 15+ min early344 flights18.4%
- Within 15 min1,008 flights53.8%
- 15–29 min late226 flights12.1%
- 30–59 min late160 flights8.5%
- 1–2 hours late100 flights5.3%
- 2+ hours late34 flights1.8%
Scale runs 0% to 100%.
Share of 1,872 completed flights by arrival against schedule.
A late pushback is often recovered here: of 620 departures that left 15 minutes late or more, 206 still arrived on time. In the other direction, 106 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at DEN.
The worst days
Worst days for Southwest on BWI to DEN
The latest arrival of the period was on 18 July 2026, 6 hours 13 minutes behind schedule; most of its delay minutes were filed as extreme weather. On three of the five worst days the largest share was filed as a late-arriving aircraft.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 18 July 2026 | 6 hours 13 minutes | Extreme weather |
| 14 June 2026 | 4 hours 53 minutes | Late-arriving aircraft |
| 6 July 2026 | 4 hours 53 minutes | Carrier |
| 27 March 2026 | 4 hours 3 minutes | Late-arriving aircraft |
| 6 September 2025 | 3 hours 58 minutes | Late-arriving aircraft |
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 26,000 reported delay minutes.
- 34%Carrier
- 31%National Airspace System
- 29%Late-arriving aircraft
- 4%Extreme weather
- 1%Security
The largest share of delay minutes, 34%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 8,872 of the 26,000 delay minutes reported here. The split is drawn from 26,064 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 85.1% on time here.
Cancellations sit at 1.82% against a national 1.89%, which is ordinary. Diversions add another 0.63%.
Connections and stage length
What a delay here costs
7.2% 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 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.
The return leg runs 74.9% on time across 1,917 flights, within 3 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 1,919 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. 1,872 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 DEN84.5%
- 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 7.05 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.