Seattle, WA · departure reliability
SEA
Seattle-Tacoma International
- Departures
- 164,759
- Period
- September 2025 to August 2026
- Carriers
- 10
- US rank
- #9 by volume
Seattle
Seattle-Tacoma International lands a B+, 2 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 164,759 flights, of which Envoy Air flew 760 at 85.3% on time.
Envoy Air is the most reliable of the ten carriers covered here at 85.3% on time across 760 flights.
Key figures
On time
79.5%
Departures arriving under 15 minutes late at their destination
Avg delay
57 min
Across delayed flights only
Cancelled
0.93%
National rate is 1.89%
Best carrier
Envoy
85.3% on time here
These figures cover 165,000 flights between September 2025 and August 2026. The median arrival is 6 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
Carrier by carrier
Which airlines run best out of SEA
The choice of carrier is not cosmetic here. Envoy Air arrives on time 85.3% of the time; JetBlue Airways manages 53.6%. Sample sizes sit next to every figure, because a two-point gap across 413 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Alaska Airlines | 76,970 | 78.5% | 47 min | 0.89% | B+ |
| Delta Air Lines | 32,382 | 80.7% | 64 min | 1.11% | B |
| SkyWest Airlines | 28,580 | 84.9% | 60 min | 0.75% | B+ |
| United Airlines | 8,683 | 79.9% | 74 min | 0.75% | B+ |
| Southwest Airlines | 8,194 | 68.2% | 50 min | 0.44% | C+ |
| American Airlines | 6,768 | 79.7% | 97 min | 1.73% | B |
| Frontier Airlines | 1,397 | 75.8% | 89 min | 2.22% | B |
| Envoy Air | 760 | 85.3% | 74 min | 0.00% | A+ |
| Hawaiian Airlines | 612 | 65.8% | 93 min | 1.47% | C |
| JetBlue Airways | 413 | 53.6% | 101 min | 4.60% | F− |
JetBlue Airways cancels 4.6% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.
Route by route
Busiest routes out of SEA
Route-level records vary far more than the airport average. These are the 25 busiest departures from SEA, each with its own on-time rate against the airport-wide 79.5%.
| Route | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SEA to LAX · Los Angeles | 7,536 | 82.0% | 59 min | 0.81% | B+ |
| SEA to PHX · Phoenix | 7,205 | 78.2% | 57 min | 0.74% | B+ |
| SEA to SFO · San Francisco | 6,817 | 59.8% | 57 min | 1.11% | D |
| SEA to ANC · Anchorage | 6,619 | 76.5% | 50 min | 0.71% | B+ |
| SEA to DEN · Denver | 6,333 | 78.3% | 58 min | 0.68% | B+ |
| SEA to LAS · Las Vegas | 5,620 | 77.6% | 56 min | 0.93% | B+ |
| SEA to ORD · Chicago | 5,538 | 76.7% | 79 min | 1.17% | B |
| SEA to DFW · Dallas-Fort Worth | 5,228 | 78.0% | 75 min | 1.66% | B |
| SEA to GEG · Spokane | 4,956 | 83.1% | 56 min | 0.93% | B+ |
| SEA to PDX · Portland | 4,826 | 82.2% | 49 min | 0.73% | B+ |
| SEA to SAN · San Diego | 4,647 | 75.0% | 47 min | 0.90% | B+ |
| SEA to SJC · San Jose | 4,425 | 80.1% | 49 min | 0.56% | B+ |
| SEA to SMF · Sacramento | 4,387 | 82.1% | 51 min | 0.39% | B+ |
| SEA to SLC · Salt Lake City | 4,098 | 83.4% | 49 min | 0.78% | B+ |
| SEA to SNA · Santa Ana | 3,945 | 84.7% | 49 min | 0.89% | B+ |
| SEA to BOI · Boise | 3,829 | 86.3% | 51 min | 0.26% | A+ |
| SEA to ATL · Atlanta | 3,294 | 84.0% | 74 min | 0.70% | B+ |
| SEA to HNL · Honolulu | 2,927 | 66.2% | 70 min | 1.13% | C |
| SEA to JFK · New York | 2,906 | 78.0% | 69 min | 3.20% | B− |
| SEA to MSP · Minneapolis | 2,676 | 87.2% | 64 min | 0.78% | A+ |
| SEA to BOS · Boston | 2,554 | 75.1% | 64 min | 1.49% | B |
| SEA to ONT · Ontario | 2,487 | 82.6% | 50 min | 1.05% | B |
| SEA to EWR · Newark | 2,264 | 83.4% | 67 min | 2.12% | B |
| SEA to FAI · Fairbanks | 2,254 | 79.0% | 49 min | 0.75% | B+ |
| SEA to AUS · Austin | 2,090 | 78.5% | 55 min | 0.81% | B+ |
Departure window
The best time of day to leave SEA
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 13 points, against 32 points between the best and worst carrier.
- 5am–8am19,528 flights88.8%
- 8am–11am34,868 flights82.1%
- 11am–2pm31,901 flights76.8%
- 2pm–5pm23,850 flights76.5%
- 5pm–8pm23,688 flights75.4%
- 8pm–5am30,924 flights79.1%
Scale runs 65% to 95%.
Book the early departure. Flights leaving between 5am–8am arrive on time 88.8% of the time, against 75.4% for the evening window. That is 13 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 34,868 flights scheduled in it.
Explore
Filter SEA departures by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On departures from Seattle (SEA), the best departure window is 5am–8am at 88.8% on time and the worst is 5pm–8pm at 75.4%, a wide gap of 13.4 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am88.8%
- 8–11am82.1%
- 11am–2pm76.8%
- 2–5pm76.5%
- 5–8pm75.4%
- 8pm–5am79.1%
best all US flightsScale 60% to 95%.
Across the year
When SEA runs late
SEA's year swings by 14 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
July is the worst month at 71.8% on time, 14 points below April, the best at 85.6%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. July was the busiest month here, with 16,214 flights.
Across the week, Tuesday is the strongest day at 83.3% on time and Thursday the weakest at 76.6%, a spread of 7 points.
SEA month by month
From Europe
Transatlantic routes into SEA
9 European airports send scheduled passenger flights to SEA, 8,290 flights a year in both directions by the DOT's international count. The DOT keeps no delay record for international flights; the UK routes carry the CAA's departure punctuality, and every route sets its departure airport's EUROCONTROL figures beside SEA's own record above.
Delay causes
Why SEA gets delayed
Carrier accounts for 43% of the 1.89 million delay minutes carriers reported here, and the remaining four split what is left.
- 43%Carrier
- 29%Late-arriving aircraft
- 23%National Airspace System
- 5%Extreme weather
- 0%Security
The largest share of delay minutes, 43%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 808,000 of the 1.89 million delay minutes reported here. The split is drawn from 1,886,796 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 88.8% on time here.
Cancellations sit at 0.93% against a national 1.89%, which is ordinary. Diversions add another 0.34%.
5.3% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
164,759 flights sit behind these numbers, which is a large enough sample that the headline rate is not moving on noise. Where a sub-group falls below 30 flights the site shows a dash instead of a percentage.
What to do with this
Flying out of SEA
Put together: the calendar is the biggest lever here, not the carrier or the hour. April runs 85.6% on time and July 71.8%, a swing of 14 points. If the dates move at all, move them out of July before you think about anything else. 162,659 completed flights over 12 months sit behind that.
Common questions
SEA delay questions
How often is Seattle (SEA) delayed?
About one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 20.5% of the 164,759 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on Seattle (SEA)?
Envoy Air leads at 85.3% on time across 760 flights. JetBlue Airways is at the other end on 53.6%, a gap of 32 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on Seattle (SEA)?
The 5am–8am departure window is the strongest at 88.8% on time. The 5pm–8pm window is the weakest at 75.4%, 13 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are July delays on Seattle (SEA)?
July is the weakest month at 71.8% on time, compared with 85.6% in April. Across the year that is 14 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- SEA to LAX — Los Angeles82.0%
- SEA to PHX — Phoenix78.2%
- SEA to SFO — San Francisco59.8%
- SEA to ANC — Anchorage76.5%
- SEA to DEN — Denver78.3%
- SEA to LAS — Las Vegas77.6%
- Alaska Airlines on-time record78.5%
- Delta Air Lines on-time record80.7%
- SkyWest Airlines on-time record84.9%
- United Airlines on-time record79.9%
- Seattle and Portland airports: why the evening flight holds up
- US airports with the biggest gap between their best and worst month
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.