Chicago, IL · departure reliability
MDW
Chicago Midway International
- Departures
- 74,246
- Period
- June 2025 to May 2026
- Carriers
- 4
- US rank
- #29 by volume
Chicago
Chicago Midway International 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 77.4%. The late ones land about an hour behind schedule. That rests on 74,246 flights, of which Delta Air Lines flew 1,406 at 86.1% on time.
Delta Air Lines is the most reliable of the four carriers covered here at 86.1% on time across 1,406 flights.
Key figures
On time
75.6%
Departures arriving under 15 minutes late at their destination
Avg delay
57 min
Across delayed flights only
Cancelled
1.41%
National rate is 1.80%
Best carrier
Delta
86.1% on time here
These figures cover 74,000 flights between June 2025 and May 2026. The median arrival is 3 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
Which airlines run best out of MDW
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 86.1% of the time; Frontier Airlines manages 73.3%. Sample sizes sit next to every figure, because a two-point gap across 1,903 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Southwest Airlines | 69,280 | 75.4% | 55 min | 1.38% | B |
| Frontier Airlines | 1,903 | 73.3% | 80 min | 1.73% | C |
| Delta Air Lines | 1,406 | 86.1% | 94 min | 2.99% | A |
| SkyWest Airlines | 1,308 | 79.2% | 80 min | 0.99% | B+ |
The spread between Delta and Frontier is 13 points, wide enough that it should decide the booking. On a hundred trips that is 13 more arrivals inside the on-time window.
Route by route
Busiest routes out of MDW
Route-level records vary far more than the airport average. These are the 25 busiest departures from MDW, each with its own on-time rate against the airport-wide 75.6%.
| Route | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| MDW to ATL · Atlanta | 3,538 | 79.7% | 67 min | 1.95% | B |
| MDW to PHX · Phoenix | 2,820 | 76.2% | 57 min | 1.56% | B |
| MDW to MCO · Orlando | 2,789 | 76.7% | 59 min | 1.40% | B |
| MDW to MSP · Minneapolis | 2,595 | 77.5% | 67 min | 1.46% | B |
| MDW to LAS · Las Vegas | 2,405 | 76.9% | 52 min | 0.96% | B+ |
| MDW to DEN · Denver | 2,392 | 72.7% | 62 min | 1.17% | C |
| MDW to LGA · New York | 2,368 | 68.9% | 59 min | 3.93% | C− |
| MDW to DAL · Dallas | 2,155 | 77.3% | 58 min | 1.86% | B |
| MDW to DCA · Washington | 2,104 | 69.5% | 59 min | 2.14% | C |
| MDW to MCI · Kansas City | 2,093 | 79.4% | 56 min | 1.29% | B |
| MDW to BNA · Nashville | 1,905 | 80.3% | 60 min | 1.26% | B |
| MDW to BWI · Baltimore | 1,856 | 78.6% | 60 min | 2.64% | B |
| MDW to HOU · Houston | 1,843 | 74.3% | 46 min | 1.19% | C |
| MDW to STL · St. Louis | 1,705 | 82.2% | 58 min | 0.94% | B+ |
| MDW to TPA · Tampa | 1,631 | 76.6% | 56 min | 1.47% | B |
| MDW to PHL · Philadelphia | 1,530 | 74.5% | 60 min | 1.31% | C |
| MDW to BOS · Boston | 1,395 | 67.7% | 61 min | 1.08% | C |
| MDW to DTW · Detroit | 1,387 | 77.1% | 59 min | 1.44% | B |
| MDW to OMA · Omaha | 1,383 | 76.9% | 53 min | 1.08% | B |
| MDW to LAX · Los Angeles | 1,355 | 70.3% | 49 min | 1.03% | C |
| MDW to AUS · Austin | 1,351 | 76.5% | 48 min | 0.74% | B+ |
| MDW to CMH · Columbus | 1,259 | 79.8% | 59 min | 1.35% | B |
| MDW to RSW · Fort Myers | 1,162 | 75.5% | 51 min | 1.12% | B |
| MDW to PIT · Pittsburgh | 1,148 | 79.9% | 59 min | 1.13% | B |
| MDW to FLL · Fort Lauderdale | 1,133 | 74.8% | 56 min | 1.59% | C |
Departure window
The best time of day to leave MDW
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 28 points, against 13 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am9,184 flights89.5%
- 8am–11am18,262 flights84.6%
- 11am–2pm12,219 flights77.8%
- 2pm–5pm10,519 flights70.8%
- 5pm–8pm13,073 flights66.9%
- 8pm–5am10,989 flights61.4%
Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 61.4% on time, against 89.5% 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.
Across the year
When MDW runs late
MDW's year swings by 17 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 67.2% on time, 17 points below September, the best at 84.1%. 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.
Across the week, Wednesday is the strongest day at 80.0% on time and Sunday the weakest at 71.2%. 9 points is a smaller lever than departure hour, but it is free.
Delay causes
Why MDW gets delayed
One category carries most of the weight here. Late-arriving aircraft accounts for 43% of the 1.01 million 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.
- 43%Late-arriving aircraft
- 33%Carrier
- 20%National Airspace System
- 4%Extreme weather
- 0%Security
43% 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 1.01 million reported delay minutes here, that single category outweighs weather by 12 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 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 89.5% on time here.
Cancellations sit at 1.41% against a national 1.80%, which is ordinary. Diversions add another 0.24%.
7.2% 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.
74,246 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.
What to do with this
Flying out of MDW
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 84.1% on time and July 67.2%, a swing of 17 points. If the dates move at all, move them out of July before you think about anything else.
Common questions
MDW delay questions
How often is Chicago (MDW) delayed?
About 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 24.4% of the 74,246 flights in this analysis, against 22.6% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on Chicago (MDW)?
Delta Air Lines leads at 86.1% on time across 1,406 flights. Frontier Airlines is at the other end on 73.3%, a gap of 13 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 Chicago (MDW)?
The 5am–8am departure window is the strongest at 89.5% on time. The 8pm–5am window is the weakest at 61.4%, 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 Chicago (MDW)?
July is the weakest month at 67.2% on time, compared with 84.1% in September. Across the year that is 17 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.