Carrier route record
WNMIA→BWI
Southwest Airlines · Miami to Baltimore
- Flights
- 1,180
- Period
- July 2025 to June 2026
- Share of route
- 52%
- Carriers
- 5
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on MIA 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 about an hour behind schedule. That rests on 1,180 flights, with a median arrival 2 minutes early.
The US average over the same twelve months is 77.6%, so there is little to separate Southwest on MIA 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 1,151 completed flights
Avg delay
57 min
Across delayed arrivals only, not all flights
Cancelled
2.03%
National rate is 1.81%
Whole route
73.6%
Every carrier on MIA to BWI, 2,284 flights
These figures cover 1,180 flights between July 2025 and June 2026. The median arrival is 2 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 MIA to BWI
Southwest flew 1,180 of the 2,284 flights on MIA to BWI, most of the route. Its 75.1% on time is 2 points better than the route as a whole, which runs 73.6%. Ranked by on-time rate it is number two of five carriers on the route, where the range runs from Envoy at 90.4% to Spirit at 52.9%. Three 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 |
|---|---|---|---|---|---|
| Envoy Airthin sample | 114 | 90.4% | 49 min | 0.00% | A+ |
| Southwest Airlines (this page) | 1,180 | 75.1% | 57 min | 2.03% | B |
| Frontier Airlinesthin sample | 265 | 74.2% | 90 min | 1.89% | C |
| American Airlines | 688 | 69.2% | 58 min | 2.03% | C |
| Spirit Airlinesthin sample | 37 | 52.9% | 107 min | 5.41% | 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 41 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 flights95.4%
- 8am–11am47 flights89.1%
- 11am–2pm320 flights73.8%
- 2pm–5pm145 flights68.8%
- 5pm–8pm301 flights54.1%
- 8pm–5am10 flights—
Scale runs 45% to 100%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 54.1% on time, against 95.4% 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 357 flights scheduled in it.
Across the year
Southwest on MIA to BWI through the year
February is the weak month at 64.9% on time, against 87.6% in January. 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. December was the busiest month here, with 106 flights.
Across the week, Wednesday is the strongest day at 83.8% on time and Sunday the weakest at 62.4%. 21 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 52% of the 16,000 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.
- 52%Late-arriving aircraft
- 23%Carrier
- 18%National Airspace System
- 7%Extreme weather
- 0%Security
52% 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 16,000 reported delay minutes here, that single category outweighs weather by 7 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 16,295 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 95.4% on time here.
Cancellations sit at 2.03% against a national 1.81%, which is ordinary. Diversions add another 0.42%.
Connections and stage length
What a delay here costs
7.5% 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 about an hour, which a normal layover absorbs.
The 946 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 runs 72.3% on time across 1,181 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 1,180 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 MIA to BWI
Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 87.6% on time and February 64.9%, a swing of 23 points. If the dates move at all, move them out of February before you think about anything else. 1,151 completed flights over 12 months sit behind that.
Related
Where to go next
- MIA to BWI, every carrier
- Southwest on BWI to MIA, the return leg
- Envoy Air on MIA to BWI90.4%
- Frontier Airlines on MIA to BWI74.2%
- American Airlines on MIA to BWI69.2%
- Southwest Airlines network-wide record
- Miami International (MIA) 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.