Carrier route record
WNMIA→BWI
Southwest Airlines · Miami to Baltimore
- Flights
- 1,188
- Period
- September 2025 to August 2026
- Share of route
- 52%
- Carriers
- 5
Historical statistics for September 2025 to August 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 C. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.3%. The late ones land about 55 minutes behind schedule. That rests on 1,188 flights, with a median arrival 1 minute early.
The US average over the same twelve months is 77.3%, 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
73.6%
Arrivals under 15 minutes late, of 1,153 completed flights
Avg delay
54 min
Across delayed arrivals only, not all flights
Cancelled
2.10%
National rate is 1.89%
Whole route
73.5%
Every carrier on MIA to BWI, 2,291 flights
These figures cover 1,188 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 MIA to BWI
Southwest flew 1,188 of the 2,291 flights on MIA to BWI, most of the route. Its 73.6% on time is about level with the route as a whole at 73.5%. Ranked by on-time rate it is number two of five carriers on the route, where the range runs from Envoy at 90.9% to American at 70.8%. 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 | 121 | 90.9% | 49 min | 0.00% | A+ |
| Southwest Airlines (this page) | 1,188 | 73.6% | 54 min | 2.10% | C |
| Frontier Airlinesthin sample | 269 | 72.2% | 84 min | 3.35% | C− |
| Spirit Airlinesthin sample | 15 | 71.4% | 149 min | 6.67% | C− |
| American Airlines | 698 | 70.8% | 66 min | 2.01% | C |
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
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 45 points, against half a point between the best and worst carrier.
- 5am–8am357 flights94.8%
- 8am–11am55 flights87.0%
- 11am–2pm301 flights75.0%
- 2pm–5pm172 flights66.1%
- 5pm–8pm294 flights49.6%
- 8pm–5am9 flights—
Scale runs 40% to 100%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 49.6% on time, against 94.8% 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 5am–8am window is the busiest, with 357 flights scheduled in it.
Across the year
Southwest on MIA to BWI through the year
July is the worst month at 57.8% on time, 30 points below January, the best at 87.6%. 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. December was the busiest month here, with 106 flights.
Across the week, Tuesday is the strongest day at 84.9% on time and Sunday the weakest at 62.3%, a spread of 23 points.
Arrival by arrival
How late Southwest on MIA to BWI runs when it is late
The 304 late arrivals split 108 under half an hour, 111 between 30 and 60 minutes, and 85 an hour or more.
- 15+ min early163 flights14.1%
- Within 15 min686 flights59.5%
- 15–29 min late108 flights9.4%
- 30–59 min late111 flights9.6%
- 1–2 hours late63 flights5.5%
- 2+ hours late22 flights1.9%
Scale runs 0% to 100%.
Share of 1,153 completed flights by arrival against schedule.
90 of 350 late departures made up the time and arrived on time, 26% of them. 44 flights left on time and still arrived late.
The worst days
Worst days for Southwest on MIA to BWI
The latest arrival of the period was on 3 August 2026, 6 hours 12 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 3 August 2026 | 6 hours 12 minutes | Late-arriving aircraft |
| 2 August 2026 | 5 hours 32 minutes | National Airspace System |
| 6 March 2026 | 5 hours 11 minutes | Late-arriving aircraft |
| 6 October 2025 | 5 hours 4 minutes | Carrier |
| 27 December 2025 | 4 hours 59 minutes | Late-arriving aircraft |
Delay causes
Why Southwest runs late on this route
Late-arriving aircraft accounts for 49% of the 16,000 delay minutes carriers reported here, and the remaining four split what is left.
- 49%Late-arriving aircraft
- 24%National Airspace System
- 23%Carrier
- 4%Extreme weather
- 0%Security
49% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 16,000 reported delay minutes here, that single category outweighs weather by 13 to one. The split is drawn from 16,440 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 94.8% on time here.
Cancellations sit at 2.10% against a national 1.89%, which is ordinary. Diversions add another 0.84%.
Connections and stage length
What a delay here costs
7.4% 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 55 minutes, 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.
The return leg runs 72.6% on time across 1,189 flights, within about a point 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 1,188 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 July 57.8%, a swing of 30 points. If the dates move at all, move them out of July before you think about anything else. 1,153 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 BWI90.9%
- Frontier Airlines on MIA to BWI72.2%
- American Airlines on MIA to BWI70.8%
- 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 7.05 million flight records
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.