Airport month record
SEAJUN
Seattle-Tacoma International in June 2026
- Departures
- 15,402
- Month
- June 2026
- National, same month
- 74.3%
- Carriers
- 9
Historical statistics for June 2026, not live status or a forecast for this year’s June. For today’s conditions at SEA, see live FAA status.
SEA in June lands a B+, 4 points better than the national rate of 74.3%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 15,402 flights, of which SkyWest Airlines flew 2,519 at 84.6% on time.
SkyWest Airlines is the most reliable of the six carriers covered here at 84.6% on time across 2,519 flights.
Key figures
On time
78.1%
Arrivals under 15 minutes late, of 15,290 completed departures
Avg delay
57 min
Across delayed arrivals only, not all flights
Cancelled
0.48%
Nationally in June: 1.65%
Whole year
79.4%
SEA across all twelve months
These figures cover 15,402 departures from Seattle-Tacoma International in June 2026. 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
June next to SEA's other months
Against SEA's own year, June ran about a point worse than the twelve-month rate of 79.4%, which makes it number nine of twelve months, best first. Cancellations were unusually low for SEA in June, at 0.48% against 0.99% across the year.
| Month | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| July 2025 | 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 (this page) | 15,402 | 78.1% | 57 min | 0.48% | B+ |
Departure window
The best time of day to leave SEA in June
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 19 points, against 26 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am1,845 flights89.7%
- 8am–11am3,162 flights83.0%
- 11am–2pm2,908 flights76.2%
- 2pm–5pm2,281 flights71.5%
- 5pm–8pm2,151 flights71.1%
- 8pm–5am3,055 flights77.9%
Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 89.7% of the time, against 71.1% for the evening window. That is 19 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 3,162 flights scheduled in it.
Across the week, Saturday is the strongest day at 81.8% on time and Sunday the weakest at 74.4%. 7 points is a smaller lever than departure hour, but it is free.
Carrier by carrier
Which airlines ran best at SEA in June
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 84.6% of the time; Southwest Airlines manages 58.8%. Sample sizes sit next to every figure, because a two-point gap across 919 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Alaska Airlines | 7,142 | 78.2% | 47 min | 0.49% | B+ |
| Delta Air Lines | 2,886 | 81.7% | 59 min | 0.45% | B+ |
| SkyWest Airlines | 2,519 | 84.6% | 50 min | 0.16% | B+ |
| Southwest Airlines | 919 | 58.8% | 52 min | 0.11% | D+ |
| United Airlines | 915 | 73.2% | 74 min | 0.55% | C+ |
| American Airlines | 707 | 73.3% | 133 min | 1.84% | C |
| Frontier Airlinesthin sample | 143 | 72.9% | 71 min | 2.10% | C |
| Envoy Airthin sample | 93 | 90.3% | 95 min | 0.00% | A+ |
| JetBlue Airwaysthin sample | 78 | 51.3% | 69 min | 0.00% | F+ |
The spread between SkyWest and Southwest is 26 points, wide enough that it should decide the booking. On a hundred trips that is 26 more arrivals inside the on-time window.
Route by route
Busiest routes out of SEA in June
| Route | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SEA to ANC · Anchorage | 665 | 76.0% | 42 min | 0.45% | B+ |
| SEA to LAX · Los Angeles | 651 | 85.0% | 53 min | 0.46% | A+ |
| SEA to DEN · Denver | 635 | 72.2% | 57 min | 1.10% | C |
| SEA to SFO · San Francisco | 633 | 39.2% | 55 min | 0.79% | F+ |
| SEA to ORD · Chicago | 582 | 72.5% | 96 min | 1.72% | C |
| SEA to PHX · Phoenix | 569 | 77.5% | 52 min | 0.18% | B+ |
| SEA to DFW · Dallas-Fort Worth | 491 | 70.0% | 101 min | 1.63% | C |
| SEA to LAS · Las Vegas | 476 | 80.0% | 57 min | 0.00% | B+ |
| SEA to SAN · San Diego | 436 | 73.2% | 42 min | 0.69% | C+ |
| SEA to SMF · Sacramento | 408 | 83.8% | 46 min | 0.00% | B+ |
| SEA to PDX · Portland | 403 | 81.9% | 42 min | 0.00% | B+ |
| SEA to SJC · San Jose | 402 | 76.3% | 48 min | 0.25% | B+ |
| SEA to GEG · Spokane | 375 | 83.1% | 44 min | 0.27% | B+ |
| SEA to SLC · Salt Lake Citythin sample | 359 | 83.8% | 46 min | 0.00% | B+ |
| SEA to SNA · Santa Anathin sample | 354 | 83.6% | 49 min | 0.00% | B+ |
| SEA to ATL · Atlantathin sample | 325 | 83.6% | 97 min | 0.00% | B+ |
| SEA to BOI · Boisethin sample | 312 | 85.6% | 38 min | 0.00% | A+ |
| SEA to BOS · Bostonthin sample | 278 | 70.8% | 56 min | 0.72% | C+ |
| SEA to JFK · New Yorkthin sample | 270 | 78.1% | 66 min | 0.74% | B+ |
| SEA to MSP · Minneapolisthin sample | 251 | 84.0% | 58 min | 0.00% | B+ |
| SEA to ONT · Ontariothin sample | 240 | 85.6% | 46 min | 1.67% | A |
| SEA to HNL · Honoluluthin sample | 237 | 68.6% | 55 min | 0.42% | C+ |
| SEA to EWR · Newarkthin sample | 225 | 83.3% | 57 min | 0.89% | B+ |
| SEA to IAH · Houstonthin sample | 217 | 85.1% | 82 min | 0.00% | A+ |
| SEA to DTW · Detroitthin sample | 209 | 91.3% | 44 min | 0.00% | A+ |
Delay causes
What held SEA up in June
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 190,000 reported delay minutes.
- 39%Carrier
- 35%Late-arriving aircraft
- 24%National Airspace System
- 2%Extreme weather
- 0%Security
35% 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 190,000 reported delay minutes here, that single category outweighs weather by 22 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 190,133 reported delay minutes.
Cancellations are rare at 0.48%, below the national 1.65% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
5.7% of arrivals land an hour or more late, close to the national 9.7%. 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 June
For a June trip through SEA: expect 78.1% on time and 0.48% cancelled, going by June 2026. The 5am–8am window was the strongest part of the day.
Related
Where to go next
- Seattle-Tacoma International (SEA), the whole year
- SEA in July69.2%
- 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%
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.