Seattle (SEA) to Missoula (MSO): On-Time Performance
Data through May 2026
Seattle (SEA) to Missoula (MSO) effectively runs on two schedules. In September 2025, 100% of arrivals were on time; in May 2025 that fell to 42% — a 58-point seasonal swing. Across the full period the route averages 72% on-time against a national 78%.
- On-time
- 72%
- arrived <15 min late
- Avg delay
- 13 min
- completed flights
- Cancelled
- 0.8%
- Flights/day
- 1.5
- last 12 months
- Duration
- 1h 28m
- scheduled
- Distance
- 389 mi
Monthly on-time trend
Best time to fly from SEA to MSO
Aim for departures around 1 p.m. (86% on-time); avoid 11 a.m. departures (58%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Monday | 69% | 13 min |
| Tuesdaybest | 78% | 9 min |
| Wednesday | 77% | 11 min |
| Thursday | 70% | 19 min |
| Friday | 69% | 13 min |
| Saturday | 76% | 11 min |
| Sunday | 69% | 17 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft36%
- Airline operations32%
- National airspace system28%
- Weather5%
Frequently asked questions
- How often are flights from SEA to MSO delayed?
- 28% of SEA–MSO flights arrived 15 or more minutes late (the US DOT definition of a delay) between 2024-06 and 2026-05. The average arrival delay across completed flights was 13 minutes.
- What is the best time of day to fly from SEA to MSO?
- Departures around 1 p.m. have the best record (86% on-time), while departures around 11 a.m. have the worst (58%). As on most US routes, delays accumulate through the day, so earlier flights are generally safer.
- How long is the flight from SEA to MSO?
- The scheduled SEA–MSO flight time averages 1h 28m over 389 miles. Actual arrival times vary — flights on this route land 15+ minutes late 28% of the time.
- How often are SEA to MSO flights cancelled?
- 0.8% of scheduled flights on this route were cancelled between 2024-06 and 2026-05, at or below the national rate of 1.6%.
- What is the worst month to fly from SEA to MSO?
- May 2025 was the roughest month in this dataset, with only 42% of arrivals on time. The best was September 2025 at 100%. If your dates are flexible, that 58-point gap is worth planning around.
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Based on 895 flights, 2024-06–2026-05. Source: US DOT Bureau of Transportation Statistics. Updated 2026-07-01.