Route profile
SEA→MDW
Flight reliability, delays and best times to fly from Seattle to Chicago, 1,733 miles.
Right now
Aviation weather is not currently a factor.
Aviation weather is not currently a factor.
Route reliability
July 2023 – July 2026
Better than 88% of comparable major US routes (4,598 compared)
Calculated from 1,853 flights. How this is calculated
SEA → MDW arrives on time 79.5% of the time; the return trip, MDW → SEA, arrives on time 65.6% of the time, a 13.9-point gap between the two directions of the same city pair.
SEA → MDW spends 22.1 minutes on the ground on a 1,733-mile trip: 17.6 minutes from pushback to wheels-up at SEA and 4.5 minutes from touchdown to gate at MDW.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What stands out
On-time performance swings unusually widely by time of day here, wider than 100% of 4,023 comparable routes.
91.9% on time for 5–9 AM departures, against 44.9% for 12–3 PM.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Ranked against every other route with the same kind of figure and at least 4,023 in the comparison.
What sets this route apart
Where SEA to MDW differs most from similar routes by hour, weekday, month and airline, July 2023 – July 2026.
SEA to MDW struggles most at 1 PM: 42.4% of its flights scheduled then arrive on time, 32.4 points behind the 74.8% on routes of similar length at the same hour. Against all other routes the gap is 34.7 points.
SEA to MDW is at its best against routes of similar length for flights scheduled at 9 AM: 94.9% arrive on time, 12.6 points ahead of the 82.3% those routes manage at that hour. Against all other routes the gap is 10.6 points.
SEA to MDW holds up on Sundays better than routes of similar length do: 82.1% on time to their 75.4%, a 6.7 points lead. Against all other routes the gap is 7.3 points.
May is kinder to SEA to MDW than to routes of similar length: 91.1% on time against 75.6%, 15.5 points better. Against all other routes the gap is 15.9 points.
In September, SEA to MDW runs 10.5 points below routes of similar length, 71.7% on time to 82.2%. Against all other routes the gap is 10.7 points.
SEA to MDW against comparable routes
July 2023 – July 2026| Measure | This route | Compared with | Them | Gap | Flights behind it |
|---|---|---|---|---|---|
| Hour: 1 PM departures | 42.4% | routes of similar length | 74.8% | −32.4 pts | 158 here, 75,745 there |
| Hour: 9 AM departures | 94.9% | routes of similar length | 82.3% | +12.6 pts | 156 here, 89,380 there |
| Weekday: Sunday | 82.1% | routes of similar length | 75.4% | +6.7 pts | 240 here, 205,192 there |
| Month: May | 91.1% | routes of similar length | 75.6% | +15.5 pts | 124 here, 120,006 there |
| Month: September | 71.7% | routes of similar length | 82.2% | −10.5 pts | 223 here, 111,128 there |
Each comparison pools the flights of other routes, with this route’s own left out. Similar length means within 15% of this route’s 1,733 miles, with at least 5 such routes. A bucket is set against the most comparable group that has enough flights: similar length, then the same origin (at least 3 routes), then all other routes. Hours, weekdays and months appear only where both sides have 120 completed flights, and airlines where both have 600. The gap must be at least 2 points and 2 standard errors, and only the largest gap each way is kept per measure. These are differences in the flights counted, not causes.
When it goes wrong
July 2023 – July 2026
31 min late
against a median of 4 min early
Percentiles over 1,853 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at MDW after arriving from SEA.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 40% | Likely to miss |
| 45 min | 20% | High risk |
| 60 min | 10% | Some risk |
| 90 min | 3.4% | Low risk |
| 120 min | 2.0% | Low risk |
This is one leg of a connection. Gate changes and the next flight's own schedule matter too. And a connection can fail before delay is even the question — this route cancels 0.27% of the time and diverts 0.59% of the time, which a late arrival never shows up in.
Chance of missing is the share of 1,837 arrivals on this route that landed later than the connection time less 30 minutes to reach the next gate.
The worst tenth of arrivals on this route land at least 31 minutes late (90th-percentile gate arrival delay), over 1,853 operations.
Any other layover length: connection checker.
Best time to fly
SEA → MDW flights departing 5–9 AM arrived on time 91.9% of the time, against 44.9% for 12–3 PM departures, a gap of 47.0 percentage points.
By departure window
By departure hour
- 12 AM to 4 AM: too few flights to score
- 5 AM: 92.9% on time from 297 flights
- 6 AM: 92.9% on time from 370 flights
- 7 AM to 8 AM: too few flights to score
- 9 AM: 94.9% on time from 157 flights
- 10 AM: 79.5% on time from 221 flights
- 11 AM to 12 PM: too few flights to score
- 1 PM: 42.4% on time from 159 flights
- 2 PM to 10 PM: too few flights to score
- 11 PM: 76.3% on time from 208 flights
Departure windows with fewer than 120 flights are not scored.
Why SEA → MDW runs late
July 2023 – July 2026
the inbound aircraft was late, so this flight started late
crew, maintenance, boarding and fueling, all within the carrier’s control
airspace and airport capacity, including weather-driven flow control
weather severe enough to stop this flight specifically
screening or terminal security incidents
Share of the delay minutes US DOT attributed to each cause for SEA → MDW. Only delays of 15 minutes or more are attributed.
Late-arriving aircraft is the largest cause on SEA → MDW, at 47.3%: flights here mostly leave late because the plane came in late, and the day shows it: 5–9 AM departures arrived on time 91.9% of the time and 12–3 PM departures 44.9%.
Airlines on this route
Carriers with at least 200 flights, by the airline that operated each one.
| Carrier | Flights | On time | Cancelled | Median delay | Severe |
|---|---|---|---|---|---|
| Southwest Airlines | 1,853 | 79.5% | 0.27% | -4 min | 3.5% |
Other ways to fly Seattle to Chicago
Airport pairs in the same two city markets, as the DOT defines them.
| Route | Flights | On time | Cancelled | Median delay | Score |
|---|---|---|---|---|---|
| SEA→ORD Seattle to Chicago | 16,300 | 77.3% | 0.95% | -5 min | 66 |
| SEA→MDW this route Seattle to Chicago | 1,853 | 79.5% | 0.27% | -4 min | 80 |
SEA → MDW is the most reliable pairing for this journey at 79.5% on time, against 77.3% for SEA → ORD.
Weekly and seasonal patterns
By day of week
Sunday is historically the most reliable day and Thursday the least, a gap of 9.1 percentage points.
Reliability over time
July 2023 – July 2026
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 81.4% against 79.6% in the 12 months before — improving by 1.8 percentage points.
Data and methodology
Calculated by FlyerIntel from 1,853 SEA → MDW flight records from the US DOT Bureau of Transportation Statistics, covering July 2023 – July 2026. Late means 15 or more minutes past scheduled arrival; cancelled and diverted flights are left out of on-time rates.
Full methodology · Data sources · Report a problem
Related research: How Long a Layover Needs to Be · Two Airlines on One Route · Best Time of Day to Fly From Major US Airports
Analysis last recomputed