Missoula (MSO) to Seattle (SEA): On-Time Performance
Data through July 2026
Missoula (MSO) to Seattle (SEA) effectively runs on two schedules. In November 2024, 93% of arrivals were on time; in August 2025 that fell to 52% — a 41-point seasonal swing. Across the full period the route averages 78% on-time against a national 78%.
- On-time
- 78%
- arrived <15 min late
- Avg delay
- 13 min
- completed flights
- Cancelled
- 0.9%
- Flights/day
- 1.8
- last 12 months
- Duration
- 1h 39m
- scheduled
- Distance
- 389 mi
Best airline from MSO to SEA
2 airlines flew this route regularly between 2024-07 and 2026-07.
| Airline | On-time | Avg delay | Cancelled | Flights |
|---|---|---|---|---|
| SkyWest Airlinesmost reliable | 85% | 8 min | 0.0% | 108 |
| Alaska Airlines | 78% | 14 min | 1.0% | 920 |
Monthly on-time trend
Best time to fly from MSO to SEA
Aim for departures around 7 a.m. (94% on-time); avoid 5 p.m. departures (73%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Monday | 75% | 13 min |
| Tuesday | 81% | 9 min |
| Wednesdaybest | 86% | 9 min |
| Thursday | 76% | 20 min |
| Friday | 75% | 14 min |
| Saturday | 84% | 10 min |
| Sunday | 72% | 15 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft57%
- Airline operations21%
- National airspace system16%
- Weather4%
- Security2%
Frequently asked questions
- How often are flights from MSO to SEA delayed?
- 22% of MSO–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 13 minutes.
- Which airline is most reliable from MSO to SEA?
- SkyWest Airlines has the best on-time record on this route at 85%, based on 108 flights. 2 airlines flew MSO–SEA frequently enough to compare in this period.
- What is the best time of day to fly from MSO to SEA?
- Departures around 7 a.m. have the best record (94% on-time), while departures around 5 p.m. have the worst (73%). As on most US routes, delays accumulate through the day, so earlier flights are generally safer.
- How long is the flight from MSO to SEA?
- The scheduled MSO–SEA flight time averages 1h 39m over 389 miles. Actual arrival times vary — flights on this route land 15+ minutes late 22% of the time.
- How often are MSO to SEA flights cancelled?
- 0.9% 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 MSO to SEA?
- August 2025 was the roughest month in this dataset, with only 52% of arrivals on time. The best was November 2024 at 93%. If your dates are flexible, that 41-point gap is worth planning around.
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Based on 1,028 flights, 2024-07–2026-07. Source: US DOT Bureau of Transportation Statistics. Updated 2026-09-28.