Carrier route record
WNBWI→MIA
Southwest Airlines · Baltimore to Miami
- Flights
- 1,181
- 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 BWI to MIA 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 77.6%. The late ones land about an hour behind schedule. That rests on 1,181 flights, with a median arrival 1 minute early.
The national on-time rate over the same period is 77.6%, so Southwest on BWI to MIA runs 5 points behind the country as a whole. Across a thousand flights that is about 53 extra late arrivals.
Key figures
On time
72.3%
Arrivals under 15 minutes late, of 1,157 completed flights
Avg delay
59 min
Across delayed arrivals only, not all flights
Cancelled
1.86%
National rate is 1.81%
Whole route
74.7%
Every carrier on BWI to MIA, 2,286 flights
These figures cover 1,181 flights between July 2025 and June 2026. Beyond the headline rate, 8.4% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
Southwest against every carrier on BWI to MIA
Southwest flew 1,181 of the 2,286 flights on BWI to MIA, most of the route. Its 72.3% on time is 2 points worse than the route as a whole, which runs 74.7%. Ranked by on-time rate it is number three of five carriers on the route, where the range runs from Envoy at 81.6% to Spirit at 61.1%. 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 | 81.6% | 62 min | 0.00% | B+ |
| American Airlines | 689 | 80.4% | 101 min | 2.32% | B |
| Southwest Airlines (this page) | 1,181 | 72.3% | 59 min | 1.86% | C |
| Frontier Airlinesthin sample | 265 | 69.4% | 89 min | 3.40% | C− |
| Spirit Airlinesthin sample | 37 | 61.1% | 64 min | 2.70% | D |
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 31 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–8am70 flights88.6%
- 8am–11am316 flights80.4%
- 11am–2pm288 flights76.3%
- 2pm–5pm140 flights63.2%
- 5pm–8pm197 flights66.3%
- 8pm–5am170 flights57.8%
Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 57.8% on time, against 88.6% 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 316 flights scheduled in it.
Across the year
Southwest on BWI to MIA through the year
July is the worst month at 60.6% on time, 26 points below September, the best at 87.0%. 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. December was the busiest month here, with 106 flights.
Across the week, Tuesday is the strongest day at 79.6% on time and Sunday the weakest at 60.8%. 19 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 19,000 reported delay minutes.
- 38%Late-arriving aircraft
- 28%National Airspace System
- 25%Carrier
- 9%Extreme weather
- 0%Security
38% 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 19,000 reported delay minutes here, that single category outweighs weather by 4 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 18,817 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 88.6% on time here.
Cancellations sit at 1.86% against a national 1.81%, which is ordinary. Diversions add another 0.17%.
Connections and stage length
What a delay here costs
8.4% 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 75.1% on time across 1,180 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 1,181 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 MIA
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 87.0% on time and July 60.6%, a swing of 26 points. If the dates move at all, move them out of July before you think about anything else. 1,157 completed flights over 12 months sit behind that.
Related
Where to go next
- BWI to MIA, every carrier
- Southwest on MIA to BWI, the return leg
- Envoy Air on BWI to MIA81.6%
- American Airlines on BWI to MIA80.4%
- Frontier Airlines on BWI to MIA69.4%
- Southwest Airlines network-wide record
- Baltimore/Washington International Thurgood Marshall (BWI) delay statistics
- Miami International (MIA) 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.