MSO to SEA flight delays
Missoula, MT (MSO) Seattle, WA (SEA) · 389 miles
610 flights · January 2025 – August 2026 · US Bureau of Transportation Statistics
81.13%
Arrived on time
Within 15 minutes of schedule
0.98%
Cancelled
Share of scheduled flights
54 min
When late, late by
Average across delayed arrivals
11 min
Delay per flight
Averaged over every flight flown
What the record says about this route
The season swings this route hard. In April it ran 39.3 points more punctual than in August — a difference bigger than the one between the best and worst airlines on most routes. If the date is flexible, it is worth more than the carrier.
The route has been getting better. The later months in the record run 14.8 points more punctual than the earlier ones, which usually means a schedule that was too tight has been given more room.
Only Alaska Airlines flies this route in the published record, so there is no choice to weigh — the route's figures and the airline's are the same figures.
The Missoula to Seattle route sits close to the middle of the record — neither notably punctual nor notably late.
Which airline should you fly on this route?
Over January 2025 – August 2026, Alaska Airlines arrived on time most often on MSO to SEA. Flights ran closest to schedule in April and worst in August.
Every airline on MSO to SEA
Ranked by how many flights each one operated. A carrier with fewer than 100 flights in the period is listed but not graded.
| Airline | Flights | On time | Cancelled | Avg delay | Grade |
|---|---|---|---|---|---|
| Alaska Airlines | 533 | 80.27% | 1.13% | 54 min | C |
| SkyWest Airlines | 77 | 87.01% | 0% | 48 min | — |
Month by month
Share of flights that arrived within 15 minutes of schedule, by month flown.
The return leg
SEA to MSO Seattle back to Missoula 82.71% on time BCommon questions
Are flights from Missoula to Seattle usually delayed?
81.13% of flights on the MSO to SEA route arrived within 15 minutes of schedule, so roughly 2 in every ten arrived late. That is better than the average route in this record.
Which airlines fly from Missoula to Seattle?
Only Alaska Airlines appears in the published record on this route, with 533 flights and 80.27% arriving on time.
How often are MSO to SEA flights cancelled?
0.98% of scheduled flights did not operate — about 10 in every thousand. That is in the normal range.
What is the best month to fly Missoula to Seattle?
April, when 90.9% of flights arrived on time. The worst was August at 51.6%.
When MSO to SEA flights are late, how late are they?
About 54 minutes on average across the flights that arrived more than 15 minutes behind schedule.
What these figures do and do not tell you
Everything on this page is counted from the flights that actually operated on MSO to SEA during January 2025 – August 2026, as reported by the airlines to the US Bureau of Transportation Statistics. "On time" is the federal definition: arriving at the gate within 15 minutes of the scheduled time.
A route's record is a description of the past, not a forecast. Weather, air traffic control and the aircraft's earlier flights that day drive most delays, and none of them are predictable from a historical rate. What the record does tell you is whether this route runs late more often than others, and which carrier on it has the better history — which is the part you can actually act on when you book.
Cancellations are counted separately from delays because they are a different problem for a traveller: a late flight still gets you there. How the grade is calculated →