Best Time to Fly SEA to MDW: On-Time Stats by Hour & Airline
Seattle/Tacoma International → Chicago Midway International
Data through July 2026 · Last updated October 18, 2026
678 flights were scheduled from Seattle (SEA) to Chicago (MDW) in the last 12 months, and 81.4% of those that flew arrived on time, 3.8 points above the US average of 77.6%.
Southwest Airlines was the only reporting airline with regular flights on this route.
Over 24 months, Saturday was the most reliable day (87% on time) and August the worst month (68%).
The cancellation rate was 0.4% (US average 1.8%).
SEA to MDW on-time performance by airline
Last 12 months. Airlines with fewer than 30 completed flights are marked “limited data”.
| Airline | On time | Avg delay when late | Cancelled | Flights |
|---|---|---|---|---|
| Southwest Airlines | 81.4% | 42 min | 0.4% | 678 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly SEA to MDW
On-time arrival % by scheduled departure hour (local time), 1,264 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 5am–6am | 93.0% | 0.9% | 215 |
| 6am–7am | 92.8% | 0.4% | 252 |
| 7am–8am | 87.5% | 0.0% | 33 |
| 8am–9am | Limited data | 22 | |
| 9am–10am | 96.0% | 0.0% | 99 |
| 10am–11am | 76.0% | 0.6% | 160 |
| 11am–12pm | 67.7% | 0.0% | 63 |
| 12pm–1pm | Limited data | 2 | |
| 1pm–2pm | 45.7% | 0.0% | 128 |
| 2pm–3pm | Limited data | 2 | |
| 3pm–4pm | Limited data | 18 | |
| 6pm–7pm | Limited data | 2 | |
| 10pm–11pm | 70.0% | 0.0% | 60 |
| 11pm–12am | 76.3% | 0.0% | 208 |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on SEA to MDW
On-time arrivals during holiday periods compared with all other days, last 24 months.
| Period | On time | vs other days | Cancelled | Flights |
|---|---|---|---|---|
| Thanksgiving week (Tue before to Mon after) | Limited data | 14 | ||
| Christmas & New Year (Dec 20 - Jan 3) | 96.7% | +12.3 pts | 0.0% | 30 |
| Summer peak (Jun 15 - Aug 15) | 69.5% | -14.8 pts | 0.6% | 353 |
| All other days | 84.3% | — | 0.2% | 867 |
Monthly on-time trend
On-time arrival % each month, with the 12-month US average for reference.
What causes delays on this route
Share of reported delay minutes, last 12 months (BTS cause categories).