Route profile
MDW→SEA
Flight reliability, delays and best times to fly from Chicago to Seattle, 1,733 miles.
Right now
Aviation weather is not currently a factor.
Weather conditions are strongly associated with delays and cancellations.
Route reliability
July 2023 – July 2026
Better than 23% of comparable major US routes (4,598 compared)
Calculated from 1,870 flights. How this is calculated · What counts as on time
MDW → SEA arrives on time 65.6% of the time; the return trip, SEA → MDW, arrives on time 79.5% of the time, a 13.9-point gap between the two directions of the same city pair.
MDW → SEA spends 26.6 minutes on the ground on a 1,733-mile trip: 15.1 minutes from pushback to wheels-up at MDW and 11.5 minutes from touchdown to gate at SEA.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What sets this route apart
Where MDW to SEA differs most from similar routes by hour, weekday, month and airline, July 2023 – July 2026.
MDW to SEA struggles most at 5 PM: 54.9% of its flights scheduled then arrive on time, 17.1 points behind the 72.0% on routes of similar length at the same hour. Against all other routes the gap is 14.9 points.
Thursday is the day MDW to SEA slips furthest against routes of similar length, 60.9% on time where they average 76.8%, 15.9 points lower. Against all other routes the gap is 15.9 points.
In June, MDW to SEA runs 18.8 points below routes of similar length, 53.6% on time to 72.4%. Against all other routes the gap is 19.1 points.
Southwest Airlines’ flights on MDW to SEA arrive on time 65.6% of the time, 9.6 points below the 75.2% it manages on its routes of similar length. Against all other routes the gap is 11.8 points.
MDW to SEA against comparable routes
July 2023 – July 2026| Measure | This route | Compared with | Them | Gap | Flights behind it |
|---|---|---|---|---|---|
| Hour: 5 PM departures | 54.9% | routes of similar length | 72.0% | −17.1 pts | 144 here, 95,002 there |
| Weekday: Thursday | 60.9% | routes of similar length | 76.8% | −15.9 pts | 274 here, 206,699 there |
| Month: June | 53.6% | routes of similar length | 72.4% | −18.8 pts | 235 here, 123,721 there |
| Airline: Southwest Airlines | 65.6% | routes of similar length | 75.2% | −9.6 pts | 1,845 here, 261,878 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
53 min late
against a median of 4 min late
Percentiles over 1,870 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at SEA after arriving from MDW.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 56% | Likely to miss |
| 45 min | 33% | Likely to miss |
| 60 min | 20% | High risk |
| 90 min | 7.8% | Some risk |
| 120 min | 4.0% | 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 0.43% of the time and diverts 0.91% of the time, which a late arrival never shows up in.
Chance of missing is the share of 1,845 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 53 minutes late (90th-percentile gate arrival delay), over 1,870 operations.
Any other layover length: connection checker.
Best time to fly
MDW → SEA flights departing 12–3 PM arrived on time 76.0% of the time, against 53.3% for 3–6 PM departures, a gap of 22.7 percentage points.
By departure window
By departure hour
- 12 AM to 7 AM: too few flights to score
- 8 AM: 73.4% on time from 144 flights
- 9 AM: 71.1% on time from 166 flights
- 10 AM: 68.2% on time from 268 flights
- 11 AM to 1 PM: too few flights to score
- 2 PM: 70.8% on time from 171 flights
- 3 PM: too few flights to score
- 4 PM: 55.3% on time from 135 flights
- 5 PM: 54.9% on time from 145 flights
- 6 PM to 8 PM: too few flights to score
- 9 PM: 56.9% on time from 218 flights
- 10 PM to 11 PM: too few flights to score
Departure windows with fewer than 120 flights are not scored.
Why MDW → SEA 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 MDW → SEA. Only delays of 15 minutes or more are attributed. What the five causes mean
Late-arriving aircraft is the largest cause on MDW → SEA, at 41.8%: flights here mostly leave late because the plane came in late, and the day shows it: 12–3 PM departures arrived on time 76.0% of the time and 3–6 PM departures 53.3%.
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 | 1,870 | 65.6% | 0.43% | 4 min | 7.9% |
Other ways to fly Chicago to Seattle
Airport pairs in the same two city markets, as the DOT defines them.
| Route | Flights | On time | Cancelled | Median delay | Score |
|---|---|---|---|---|---|
| ORD→SEA Chicago to Seattle | 16,311 | 74.0% | 1.00% | -4 min | 61 |
| MDW→SEA this route Chicago to Seattle | 1,870 | 65.6% | 0.43% | 4 min | 55 |
ORD → SEA is the most reliable pairing for this journey at 74.0% on time, against 65.6% for MDW → SEA.
Flying to SEA from the Chicago area? Compare MDW, ORD for SEA, with the same test for what counts as a real difference.
Weekly and seasonal patterns
By day of week
Wednesday is historically the most reliable day and Friday the least, a gap of 11.3 percentage points.
Reliability over time
July 2023 – July 2026
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 63.4% against 66.5% in the 12 months before — declining by 3.1 percentage points.
Data and methodology
Calculated by FlyerIntel from 1,870 MDW → SEA 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