Seattle (SEA) to Chicago (MDW): On-Time Performance
Data through July 2026
When you fly SEA to MDW matters as much as anything else about the booking: the route swung from 100% on-time in November 2024 to just 65% in July 2024. Across the full period the route averages 79% on-time against a national 78%. Morning departures also hold up better than evening ones (87% vs 73%), which matters most in the rough months.
- On-time
- 79%
- arrived <15 min late
- Avg delay
- 10 min
- completed flights
- Cancelled
- 0.3%
- Flights/day
- 1.9
- last 12 months
- Duration
- 4h 0m
- scheduled
- Distance
- 1,733 mi
Monthly on-time trend
Best time to fly from SEA to MDW
Aim for departures around 9 a.m. (96% on-time); avoid 1 p.m. departures (44%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Monday | 79% | 9 min |
| Tuesday | 82% | 9 min |
| Wednesday | 82% | 10 min |
| Thursday | 70% | 15 min |
| Friday | 76% | 9 min |
| Saturdaybest | 85% | 8 min |
| Sunday | 81% | 11 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft48%
- Airline operations37%
- National airspace system13%
- Weather2%
- Security1%
Frequently asked questions
- How often are flights from SEA to MDW delayed?
- 21% of SEA–MDW flights arrived 15 or more minutes late (the US DOT definition of a delay) between 2024-07 and 2026-07. The average arrival delay across completed flights was 10 minutes.
- What is the best time of day to fly from SEA to MDW?
- Departures around 9 a.m. have the best record (96% on-time), while departures around 1 p.m. have the worst (44%). As on most US routes, delays accumulate through the day, so earlier flights are generally safer.
- How long is the flight from SEA to MDW?
- The scheduled SEA–MDW flight time averages 4h 0m over 1,733 miles. Actual arrival times vary — flights on this route land 15+ minutes late 21% of the time.
- How often are SEA to MDW flights cancelled?
- 0.3% of scheduled flights on this route were cancelled between 2024-07 and 2026-07, at or below the national rate of 1.6%.
- What is the worst month to fly from SEA to MDW?
- July 2024 was the roughest month in this dataset, with only 65% of arrivals on time. The best was November 2024 at 100%. If your dates are flexible, that 35-point gap is worth planning around.
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Based on 1,352 flights, 2024-07–2026-07. Source: US DOT Bureau of Transportation Statistics. Updated 2026-09-28.