Carrier performance at one airport
WN→BWI
Southwest Airlines at Baltimore/Washington International Thurgood Marshall
- Departures
- 72,526
- Period
- June 2025 to May 2026
- Routes
- 25
- Rank here
- #5 of 9
Southwest Airlines at Baltimore lands a B, level with the national rate of 77.4%. Roughly one flight in four arrive 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 72,526 flights, of which Delta Air Lines flew 5,322 at 84.8% on time.
Measured against the airport rather than the country, Southwest Airlines runs half a point behind the 77.3% weighted average across all carriers at BWI. That is the comparison worth making: every operator here works the same runways, the same airspace and the same weather.
Key figures
On time
77.0%
71,250 completed departures
Avg delay
58 min
Across delayed flights only
Cancelled
1.57%
At BWI, this carrier only
Rank here
#5
Of 9 carriers clearing the floor at BWI
These figures cover 73,000 flights between June 2025 and May 2026. The median arrival is 4 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.
Against the competition
Every carrier at BWI, ranked
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 84.8% of the time; Frontier Airlines manages 67.3%. Sample sizes sit next to every figure, because a two-point gap across 3,185 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 5,322 | 84.8% | 89 min | 1.82% | B |
| United Airlines | 4,149 | 81.4% | 79 min | 0.99% | B+ |
| Republic Airways | 1,338 | 81.3% | 85 min | 2.99% | B |
| American Airlines | 3,498 | 78.7% | 106 min | 2.43% | B |
| Southwest Airlines (this page) | 72,526 | 77.0% | 58 min | 1.57% | B |
| Spirit Airlines | 3,671 | 76.2% | 80 min | 2.72% | B |
| Envoy Air | 1,055 | 74.4% | 80 min | 3.41% | C− |
| Alaska Airlines | 618 | 68.0% | 46 min | 0.81% | C+ |
| Frontier Airlines | 3,185 | 67.3% | 94 min | 3.17% | C− |
Envoy Air cancels 3.4% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.
Route by route
Where Southwest Airlines flies from BWI
Southwest Airlines operates 25 routes out of BWI with enough volume to report. Route records inside one carrier at one airport still spread widely, because a short shuttle and a transcontinental have very different exposure to a late inbound.
| Route | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| BWI to MCO · Orlando | 3,570 | 76.6% | 65 min | 2.10% | B |
| BWI to BOS · Boston | 2,381 | 72.0% | 64 min | 2.56% | C |
| BWI to TPA · Tampa | 2,347 | 79.5% | 63 min | 1.66% | B |
| BWI to FLL · Fort Lauderdale | 2,142 | 75.5% | 59 min | 1.49% | B |
| BWI to DEN · Denver | 1,911 | 72.2% | 57 min | 1.52% | C |
| BWI to PVD · Providence | 1,882 | 78.2% | 58 min | 1.97% | B |
| BWI to DAL · Dallas | 1,824 | 76.5% | 60 min | 1.86% | B |
| BWI to RDU · Raleigh | 1,793 | 80.0% | 58 min | 2.34% | B |
| BWI to BDL · Hartford | 1,763 | 81.2% | 56 min | 1.93% | B |
| BWI to BNA · Nashville | 1,763 | 80.7% | 58 min | 1.76% | B |
| BWI to MDW · Chicago | 1,755 | 76.2% | 60 min | 1.99% | B |
| BWI to ALB · Albany | 1,740 | 80.4% | 53 min | 1.49% | B |
| BWI to BUF · Buffalo | 1,730 | 75.4% | 53 min | 1.68% | B |
| BWI to MHT · Manchester | 1,710 | 81.7% | 58 min | 1.17% | B |
| BWI to LAS · Las Vegas | 1,635 | 78.8% | 56 min | 1.22% | B |
| BWI to ATL · Atlanta | 1,580 | 77.0% | 62 min | 1.39% | B |
| BWI to ORF · Norfolk | 1,531 | 78.7% | 50 min | 1.37% | B |
| BWI to HOU · Houston | 1,464 | 75.9% | 54 min | 1.57% | B |
| BWI to RSW · Fort Myers | 1,452 | 75.0% | 57 min | 1.65% | B |
| BWI to JAX · Jacksonville | 1,410 | 75.6% | 57 min | 1.35% | B |
| BWI to PWM · Portland | 1,342 | 78.0% | 50 min | 1.27% | B |
| BWI to PHX · Phoenix | 1,308 | 76.8% | 54 min | 0.92% | B+ |
| BWI to SRQ · Sarasota | 1,298 | 79.2% | 65 min | 1.39% | B |
| BWI to AUS · Austin | 1,285 | 77.3% | 53 min | 1.79% | B |
| BWI to STL · St. Louis | 1,283 | 82.7% | 64 min | 1.17% | B |
Departure window
Best time of day for this operation
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 28 points, against 18 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am7,094 flights92.0%
- 8am–11am17,745 flights88.3%
- 11am–2pm9,544 flights81.1%
- 2pm–5pm12,913 flights72.5%
- 5pm–8pm12,161 flights66.9%
- 8pm–5am13,069 flights64.1%
Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 64.1% on time, against 92.0% 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.
Across the year
Seasonal pattern
July is the worst month at 65.4% on time, 20 points below September, the best at 85.4%. 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.
Delay causes
What holds this operation up
- 42%Late-arriving aircraft
- 32%Carrier
- 19%National Airspace System
- 6%Extreme weather
- 1%Security
42% 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 954,000 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.
Cancellations sit at 1.57% against a national 1.80%, which is ordinary. Diversions add another 0.19%.
7.0% of arrivals land an hour or more late, close to the national 8.2%. 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 are the about an hour kind, which a normal layover absorbs.
72,526 flights sit behind these numbers, which is a large enough sample that the headline rate is not moving on noise. Where a sub-group falls below 30 flights the site shows a dash instead of a percentage.
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 85.4% on time and July 65.4%, a swing of 20 points. If the dates move at all, move them out of July before you think about anything else.
Common questions
Southwest Airlines at BWI
How often is Southwest Airlines at BWI delayed?
Roughly one flight in four arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 23.0% of the 72,526 flights in this analysis, against 22.6% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on Southwest Airlines at BWI?
Delta Air Lines leads at 84.8% on time across 5,322 flights. Frontier Airlines is at the other end on 67.3%, a gap of 18 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on Southwest Airlines at BWI?
The 5am–8am departure window is the strongest at 92.0% on time. The 8pm–5am window is the weakest at 64.1%, 28 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are July delays on Southwest Airlines at BWI?
July is the weakest month at 65.4% on time, compared with 85.4% in September. Across the year that is 20 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
Source: US DOT Bureau of Transportation Statistics, on-time performance data, June 2025 to May 2026. Updated monthly. How this data is collected.