Route reliability record
BWI→MDW
Baltimore to Chicago
- Flights
- 1,844
- Period
- July 2025 to June 2026
- Distance
- 611 mi
- Carriers
- 2
This route sits in the middle of the pack with a B. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 1,844 BWI to MDW flights, with a median arrival 4 minutes early.
Best time to fly BWI to MDW: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 92.5% of the time and Wednesday flights 79.7%, against 75.7% for the route overall.
The US average over the same twelve months is 77.6%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
75.7%
Arrivals under 15 minutes late, of 1,795 completed flights
Avg delay
64 min
Across delayed arrivals only, not all flights
Cancelled
2.11%
National rate is 1.81%
Best carrier
Southwest
76.0% on time across 1,760 flights
These figures cover 1,844 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
Which airline is most reliable on BWI to MDW
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 |
|---|---|---|---|---|---|
| Southwest Airlines | 1,760 | 76.0% | 62 min | 2.10% | B |
| Frontier Airlinesthin sample | 84 | 69.1% | 90 min | 2.38% | C |
Best ways to make this trip
The most reliable ways to fly Baltimore to Chicago
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 4 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. DCA → MDWWashington to Chicago | Southwest Airlines | 75.1% | 77.2% | 2.76% | 5am–8am, Sat | — |
| 2. IAD → ORDWashington to Chicago | United Airlines | 74.6% | 75.2% | 0.83% | 5am–8am, Tue | UA 1775 08:20 |
| 3. BWI → MDWBaltimore to Chicago | Southwest Airlines | 74.4% | 76.0% | 2.10% | 5am–8am, Wed (route) | — |
| 4. BWI → ORDBaltimore to Chicago | United Airlines | 74.1% | 75.1% | 1.31% | 5am–8am, Tue | UA 590 17:20 |
| 5. DCA → ORDWashington to Chicago | United Airlines | 72.0% | 73.6% | 2.21% | 8am–11am, Sat | UA 2201 10:30 |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 37 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–8am323 flights92.5%
- 8am–11am265 flights86.2%
- 11am–2pm257 flights80.5%
- 2pm–5pm336 flights75.3%
- 5pm–8pm374 flights65.7%
- 8pm–5am289 flights55.8%
Scale runs 45% to 100%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 55.8% on time, against 92.5% 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 5pm–8pm window is the busiest, with 374 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 25 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
July is the worst month at 62.0% on time, 25 points below January, the best at 86.7%. 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. July was the busiest month here, with 187 flights.
Across the week, Wednesday is the strongest day at 79.7% on time and Monday the weakest at 71.4%. 8 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Late-arriving aircraft accounts for 50% of the 28,000 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.
- 50%Late-arriving aircraft
- 26%Carrier
- 19%National Airspace System
- 5%Extreme weather
- 0%Security
50% 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 28,000 reported delay minutes here, that single category outweighs weather by 9 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 27,754 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 92.5% on time here.
Cancellations sit at 2.11% against a national 1.81%, which is ordinary. Diversions add another 0.54%.
Connections and stage length
What a delay here actually 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 611 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 is a different operation and performs like one: it runs 78.9% on time across 1,852 flights, 3 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 3 points of difference.
The sample behind these figures is 1,844 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.
Work out the risk of missing a connection in MDW after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 86.7% on time and July 62.0%, a swing of 25 points. If the dates move at all, move them out of July before you think about anything else. 1,795 completed flights over 12 months sit behind that.
Common questions
BWI to MDW questions
How often is BWI to MDW delayed?
About one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 24.3% of the 1,844 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
How reliable is BWI to MDW compared with the rest of the country?
75.7% of flights arrive on time here against a national 77.6%, a difference of 2 points against it. That is worth a B on this site's grading scale.
What time of day has the fewest delays on BWI to MDW?
The 5am–8am departure window is the strongest at 92.5% on time. The 8pm–5am window is the weakest at 55.8%, 37 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 BWI to MDW?
July is the weakest month at 62.0% on time, compared with 86.7% in January. Across the year that is 25 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
- MDW to BWI — the return legseparate record
- Baltimore/Washington International Thurgood Marshall (BWI) delay statistics
- Chicago Midway International (MDW) delay statistics
- BWI to ATL, a related route80.6%
- ATL to MDW, a related route76.3%
- BWI to MCO, a related route75.6%
- Southwest Airlines on-time record76.0%
- Frontier Airlines on-time record69.1%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. BWI to MDW and MDW to BWI are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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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.