Airport month record
SEAJUL
Seattle-Tacoma International in July 2025
- Departures
- 16,577
- Month
- July 2025
- National, same month
- 71.1%
- Carriers
- 11
Historical statistics for July 2025, not live status or a forecast for this year’s July. For today’s conditions at SEA, see live FAA status.
SEA in July sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 2 points worse than the national rate of 71.1%. The late ones land about an hour behind schedule. That rests on 16,577 flights, of which SkyWest Airlines flew 2,876 at 83.5% on time.
SkyWest Airlines is the most reliable of the six carriers covered here at 83.5% on time across 2,876 flights.
Key figures
On time
69.2%
Arrivals under 15 minutes late, of 16,263 completed departures
Avg delay
57 min
Across delayed arrivals only, not all flights
Cancelled
1.38%
Nationally in July: 2.45%
Whole year
79.4%
SEA across all twelve months
These figures cover 16,577 departures from Seattle-Tacoma International in July 2025. On time means an arrival less than 15 minutes after the scheduled gate time, the DOT's threshold, and the national comparison uses every US departure in the same month rather than the whole year.
Against the year
July next to SEA's other months
Against SEA's own year, July ran 10 points worse than the twelve-month rate of 79.4%, which makes it the worst of the twelve months in the data.
| Month | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| July 2025 (this page) | 16,577 | 69.2% | 57 min | 1.38% | C |
| August 2025 | 15,970 | 73.6% | 51 min | 0.66% | C+ |
| September 2025 | 14,552 | 82.9% | 50 min | 0.29% | B+ |
| October 2025 | 13,859 | 82.9% | 58 min | 1.16% | B |
| November 2025 | 12,616 | 81.9% | 58 min | 1.69% | B |
| December 2025 | 13,023 | 74.0% | 59 min | 1.02% | C |
| January 2026 | 11,927 | 81.6% | 60 min | 1.91% | B |
| February 2026 | 11,000 | 84.4% | 56 min | 0.78% | B+ |
| March 2026 | 12,830 | 80.2% | 64 min | 2.23% | B |
| April 2026 | 12,864 | 85.6% | 56 min | 0.17% | A+ |
| May 2026 | 14,564 | 82.2% | 52 min | 0.41% | B+ |
| June 2026 | 15,402 | 78.1% | 57 min | 0.48% | B+ |
Departure window
The best time of day to leave SEA in July
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 26 points, against 23 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am1,808 flights88.1%
- 8am–11am3,476 flights76.6%
- 11am–2pm3,017 flights63.1%
- 2pm–5pm2,382 flights64.5%
- 5pm–8pm2,480 flights62.4%
- 8pm–5am3,414 flights65.4%
Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 62.4% on time, against 88.1% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 8am–11am window is the busiest, with 3,476 flights scheduled in it.
Across the week, Saturday is the strongest day at 74.1% on time and Monday the weakest at 63.6%. 10 points is a smaller lever than departure hour, but it is free.
Carrier by carrier
Which airlines ran best at SEA in July
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 83.5% of the time; Alaska Airlines manages 61.0%. Sample sizes sit next to every figure, because a two-point gap across 7,510 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Alaska Airlines | 7,510 | 61.0% | 48 min | 2.09% | D |
| Delta Air Lines | 2,970 | 79.2% | 62 min | 0.91% | B+ |
| SkyWest Airlines | 2,876 | 83.5% | 47 min | 0.14% | B+ |
| United Airlines | 1,034 | 72.5% | 75 min | 1.45% | C |
| Southwest Airlines | 988 | 62.3% | 57 min | 0.30% | D+ |
| American Airlines | 649 | 71.6% | 120 min | 2.00% | C |
| Hawaiian Airlinesthin sample | 217 | 49.5% | 72 min | 1.38% | F |
| Frontier Airlinesthin sample | 152 | 57.8% | 90 min | 3.29% | D− |
| JetBlue Airwaysthin sample | 93 | 34.1% | 162 min | 1.08% | F |
| Envoy Airthin sample | 57 | 82.1% | 50 min | 0.00% | B+ |
| Spirit Airlinesthin sample | 31 | 67.7% | 34 min | 0.00% | C+ |
The spread between SkyWest and Alaska is 23 points, wide enough that it should decide the booking. On a hundred trips that is 23 more arrivals inside the on-time window.
Route by route
Busiest routes out of SEA in July
| Route | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SEA to ANC · Anchorage | 745 | 65.7% | 47 min | 2.15% | C |
| SEA to DEN · Denver | 670 | 61.3% | 71 min | 1.19% | D |
| SEA to LAX · Los Angeles | 642 | 77.8% | 62 min | 1.25% | B |
| SEA to SFO · San Francisco | 639 | 70.7% | 59 min | 1.88% | C |
| SEA to ORD · Chicago | 623 | 65.2% | 63 min | 1.28% | C |
| SEA to PHX · Phoenix | 621 | 73.7% | 49 min | 0.48% | C+ |
| SEA to GEG · Spokane | 544 | 69.9% | 46 min | 0.92% | C+ |
| SEA to LAS · Las Vegas | 521 | 69.1% | 52 min | 0.77% | C+ |
| SEA to DFW · Dallas-Fort Worth | 505 | 64.8% | 94 min | 1.58% | D |
| SEA to SMF · Sacramento | 455 | 73.5% | 54 min | 0.66% | C+ |
| SEA to SAN · San Diego | 446 | 76.0% | 42 min | 2.69% | B |
| SEA to SJC · San Jose | 425 | 72.3% | 49 min | 2.35% | C |
| SEA to BOI · Boise | 394 | 79.9% | 47 min | 0.25% | B+ |
| SEA to SLC · Salt Lake City | 394 | 76.6% | 53 min | 1.02% | B |
| SEA to PDX · Portland | 392 | 76.0% | 45 min | 0.26% | B+ |
| SEA to SNA · Santa Ana | 378 | 79.7% | 41 min | 2.38% | B |
| SEA to ATL · Atlantathin sample | 347 | 69.3% | 64 min | 0.29% | C+ |
| SEA to ONT · Ontariothin sample | 302 | 72.3% | 59 min | 3.31% | C− |
| SEA to MSP · Minneapolisthin sample | 295 | 75.4% | 48 min | 0.68% | B+ |
| SEA to JFK · New Yorkthin sample | 279 | 49.2% | 65 min | 2.87% | F |
| SEA to BOS · Bostonthin sample | 274 | 59.5% | 110 min | 1.46% | D |
| SEA to HNL · Honoluluthin sample | 248 | 50.4% | 65 min | 2.42% | F |
| SEA to FAI · Fairbanksthin sample | 247 | 67.5% | 51 min | 2.83% | C |
| SEA to IAD · Washingtonthin sample | 245 | 69.4% | 68 min | 0.41% | C+ |
| SEA to IAH · Houstonthin sample | 236 | 63.6% | 52 min | 2.12% | D |
Delay causes
What held SEA up in July
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 283,000 reported delay minutes.
- 39%Carrier
- 37%Late-arriving aircraft
- 22%National Airspace System
- 2%Extreme weather
- 0%Security
37% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 283,000 reported delay minutes here, that single category outweighs weather by 19 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 283,211 reported delay minutes.
Cancellations sit at 1.38% against a national 2.45%, which is ordinary. Diversions add another 0.52%.
8.1% of arrivals land an hour or more late, close to the national 12.1%. That is the figure that decides a connection, and it says 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.
What to do with this
Flying from SEA in July
For a July trip through SEA: plan on this being one of the airport's harder months. The 5am–8am departures held up best at 88.1% on time, and with 8.1% of arrivals an hour or more late, a connection here deserves more slack than the same trip in April would.
Related
Where to go next
- Seattle-Tacoma International (SEA), the whole year
- SEA in August73.6%
- SEA in September82.9%
- SEA in October82.9%
- SEA in November81.9%
- SEA in December74.0%
- SEA in January81.6%
- SEA in February84.4%
- SEA in March80.2%
- SEA in April85.6%
- SEA in May82.2%
- SEA in June78.1%
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.