Best Time to Fly MDW to SEA: On-Time Stats by Hour & Airline
Chicago Midway International → Seattle/Tacoma International
Data through July 2026 · Last updated October 18, 2026
678 flights were scheduled from Chicago (MDW) to Seattle (SEA) in the last 12 months, and 63.5% of those that flew arrived on time, 14.1 points below the US average of 77.6%.
Southwest Airlines was the only reporting airline with regular flights on this route.
January has been the best month (81% on time) and Friday the weakest day of the week (57%).
0.6% of flights were cancelled, versus 1.8% nationally.
MDW to SEA 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 | 63.5% | 52 min | 0.6% | 678 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly MDW to SEA
On-time arrival % by scheduled departure hour (local time), 1,264 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 7am–8am | 72.5% | 0.0% | 40 |
| 8am–9am | 75.3% | 0.0% | 90 |
| 9am–10am | 77.1% | 0.0% | 118 |
| 10am–11am | 67.6% | 0.5% | 220 |
| 11am–12pm | 75.7% | 0.0% | 71 |
| 12pm–1pm | 72.7% | 0.0% | 44 |
| 1pm–2pm | 71.1% | 0.0% | 45 |
| 2pm–3pm | 67.6% | 0.0% | 75 |
| 3pm–4pm | 40.0% | 0.0% | 41 |
| 4pm–5pm | 50.7% | 0.0% | 76 |
| 5pm–6pm | 53.7% | 0.0% | 109 |
| 6pm–7pm | Limited data | 19 | |
| 7pm–8pm | Limited data | 11 | |
| 8pm–9pm | 64.0% | 0.0% | 51 |
| 9pm–10pm | 58.7% | 0.0% | 184 |
| 10pm–11pm | 56.7% | 4.3% | 70 |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on MDW to SEA
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) | 63.3% | -5.7 pts | 0.0% | 30 |
| Summer peak (Jun 15 - Aug 15) | 54.8% | -14.3 pts | 0.8% | 353 |
| All other days | 69.0% | — | 0.1% | 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).