Chicago (MDW) to Seattle (SEA): On-Time Performance
Data through July 2026
When you fly MDW to SEA matters as much as anything else about the booking: the route swung from 90% on-time in April 2025 to just 25% in March 2026. Across the full period the route averages 65% on-time against a national 78%. Morning departures also hold up better than evening ones (73% vs 58%), which matters most in the rough months.
- On-time
- 65%
- arrived <15 min late
- Avg delay
- 18 min
- completed flights
- Cancelled
- 0.5%
- Flights/day
- 1.9
- last 12 months
- Duration
- 4h 31m
- scheduled
- Distance
- 1,733 mi
Monthly on-time trend
Best time to fly from MDW to SEA
Aim for departures around 9 a.m. (78% on-time); avoid 3 p.m. departures (48%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Monday | 63% | 20 min |
| Tuesdaybest | 72% | 15 min |
| Wednesday | 71% | 14 min |
| Thursday | 59% | 22 min |
| Friday | 58% | 24 min |
| Saturday | 64% | 17 min |
| Sunday | 66% | 16 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft42%
- Airline operations30%
- National airspace system23%
- Weather5%
Frequently asked questions
- How often are flights from MDW to SEA delayed?
- 35% of MDW–SEA 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 18 minutes.
- What is the best time of day to fly from MDW to SEA?
- Departures around 9 a.m. have the best record (78% on-time), while departures around 3 p.m. have the worst (48%). As on most US routes, delays accumulate through the day, so earlier flights are generally safer.
- How long is the flight from MDW to SEA?
- The scheduled MDW–SEA flight time averages 4h 31m over 1,733 miles. Actual arrival times vary — flights on this route land 15+ minutes late 35% of the time.
- How often are MDW to SEA flights cancelled?
- 0.5% 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 MDW to SEA?
- March 2026 was the roughest month in this dataset, with only 25% of arrivals on time. The best was April 2025 at 90%. If your dates are flexible, that 65-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.