71% of flights from San Francisco to Seattle arrived on time over the past 12 months. That is worse than the typical U.S. route. The 5 a.m. departures ran on time 94% of the time; the 8 a.m. ones 58%. Most reliable airline: United Airlines (75%). 9% of flights arrived more than an hour late or not at all.
How late?
The on-time rate treats a flight 20 minutes late the same as one 5 hours late. Here's the split for SFO → SEA: when a flight was late, it was under 45 minutes late 60% of the time. About 1 in 14 flights landed an hour or more late, and 1 in 97 three hours or more; 1.1% were cancelled outright.
- On time or early71%
- 15–30 min late11%
- 30–60 min late9.4%
- 1–2 hours late5.0%
- 2–3 hours late1.3%
- 3+ hours late1.0%
- Diverted0.1%
- Cancelled1.1%
Share of all 6,824 scheduled flights, past 12 months, by arrival time against schedule.
By airline
| Airline | Flights | On time | Cancelled | Typical arrival | 1h+ late | Avg when late | Operated by |
|---|---|---|---|---|---|---|---|
| Alaska Airlines | 2,735 | 68% | 1.3% | +1 min | 7.2% | +54 min | Alaska Airlines 100%, Horizon Air 0%, SkyWest 0% |
| United Airlines | 2,336 | 75% | 0.5% | −6 min | 7.1% | +57 min | United Airlines 88%, SkyWest 12% |
| Delta Air Lines | 1,750 | 73% | 1.5% | −5 min | 8.1% | +58 min | Delta Air Lines 56%, SkyWest 44% |
| Southwest Airlines | 3 | — | — | — | — | — | Southwest Airlines |
Airline = the name on the ticket. Regional flights (e.g. "Delta Connection") count under the ticketing airline, and the operator is listed.
Best time of day to fly
On-time rate by scheduled departure hour (local time at SFO). Delays build through the day as late planes knock on, so early flights usually do best.
By airline and hour
| Departs | Alaska Airlines | United Airlines | Delta Air Lines |
|---|---|---|---|
| 5 a.m. | — | — | 94% |
| 6 a.m. | 89% | — | 93% |
| 7 a.m. | 89% | — | — |
| 8 a.m. | 60% | — | — |
| 9 a.m. | 69% | 87% | — |
| 10 a.m. | 35% | 65% | 67% |
| 11 a.m. | 75% | — | — |
| noon | 51% | 79% | — |
| 1 p.m. | — | 82% | 70% |
| 2 p.m. | 71% | 73% | 74% |
| 3 p.m. | 63% | — | — |
| 4 p.m. | 72% | 76% | 71% |
| 5 p.m. | 63% | — | 52% |
| 6 p.m. | 66% | 78% | — |
| 7 p.m. | 75% | — | — |
| 8 p.m. | 60% | 69% | 64% |
| 9 p.m. | — | 63% | — |
| 10 p.m. | — | 70% | — |
Last flight of the day
On SFO → SEA, each airline's last flight of the day was cancelled 0.7% of the time, against 1.1% for its earlier flights, so here the last flight is actually the safer one. It arrived 3+ hours late 0.7% of the time (earlier flights: 1.1%). It matters more than the numbers suggest. Miss an earlier flight and there's another one that evening; miss the last one and you're usually waiting until morning.
| Airline | Last departure | Last: cancelled | Last: 3h+ late | Earlier: cancelled | Next morning |
|---|---|---|---|---|---|
| Alaska Airlines | 8:28 p.m. | 0.8% | 0.8% | 1.4% | first flight 6:03 a.m. |
| Delta Air Lines | 8:59 p.m. | 0.5% | 1.4% | 1.8% | first flight 5:55 a.m. |
| United Airlines | 10:59 p.m. | 0.8% | 0.0% | 0.5% | first flight 7:00 a.m. |
Last flight = the airline's last scheduled departure on this route that day, on days it flies the route at least twice; past 12 months. Times are typical scheduled times over the latest three months.
By month
Each calendar month pooled over 2023–2026. Best: November (82%). Worst: June (64%).
By day of week
| Day | Flights | On time | Cancelled |
|---|---|---|---|
| Monday | 1,062 | 67% | 1.0% |
| Tuesday | 928 | 78% | 0.3% |
| Wednesday | 951 | 74% | 0.6% |
| Thursday | 1,013 | 65% | 0.9% |
| Friday | 1,010 | 67% | 2.1% |
| Saturday | 847 | 79% | 1.8% |
| Sunday | 1,013 | 72% | 0.9% |
Why flights were late
Share of delay minutes on flights 15+ minutes late, as reported to BTS by the airlines.
Cancellations: airline 45 · air traffic/airport 15 · weather 14
Month by month
Flight numbers on this route
Regular flights with at least 120 scheduled trips in the past year. Sorted by departure time.
| Flight | Departs | Flights | On time | Cancelled | Typical arrival | Operated by |
|---|---|---|---|---|---|---|
| DL 2721 | 5:55 a.m. | 349 | 94% | 1.4% | −20 min | Delta Air Lines |
| AS 68 | 7:03 a.m. | 173 | 84% | 0.6% | −4 min | Alaska Airlines |
| AS 1327 | 9:00 a.m. | 258 | 66% | 1.9% | +1 min | Alaska Airlines |
| AS 656 | 9:00 a.m. | 233 | 52% | 3.0% | +11 min | Alaska Airlines |
| AS 580 | 12:00 p.m. | 234 | 76% | 3.9% | −8 min | Alaska Airlines |
| DL 1412 | 1:45 p.m. | 346 | 73% | 1.5% | −3 min | Delta Air Lines |
| AS 1340 | 3:50 p.m. | 214 | 64% | 0.9% | +1 min | Alaska Airlines |
| UA 2279 | 4:10 p.m. | 296 | 76% | 0.0% | −8 min | United Airlines |
| DL 3707 | 4:37 p.m. | 331 | 64% | 1.2% | +3 min | SkyWest |
| AS 758 | 5:38 p.m. | 297 | 67% | 0.3% | 0 min | Alaska Airlines |
| AS 591 | 8:28 p.m. | 246 | 67% | 0.4% | +2 min | Alaska Airlines |
| UA 1007 | 8:58 p.m. | 236 | 65% | 0.4% | +4 min | United Airlines |
| DL 3991 | 8:59 p.m. | 296 | 64% | 0.7% | +4 min | SkyWest |
| UA 5579 | 10:35 p.m. | 142 | 70% | 0.7% | −8 min | SkyWest |
Worst days in the past year
| Date | Flights | On time | Cancelled |
|---|---|---|---|
| Jul 16, 2026 | 22 | 23% | 0 |
| May 15, 2026 | 19 | 26% | 0 |
| Jul 27, 2026 | 22 | 27% | 1 |
| Dec 21, 2025 | 18 | 28% | 1 |
| Jan 5, 2026 | 18 | 28% | 0 |
Nearby airport alternatives
Other ways to make the same trip, using airports within 60 miles of San Francisco or Seattle. SJC → SEA has been 11 points more reliable.
| Route | Flights | On time | Cancelled |
|---|---|---|---|
| SFO → SEA (this route) | 6,824 | 71% | 1.1% |
| SJC → SEA San Jose to Seattle-Tacoma | 4,461 | 82% | 0.6% |
| OAK → SEA Oakland to Seattle-Tacoma | 2,304 | 77% | 1.0% |
| SFO → PAE San Francisco to Seattle Paine | 621 | 54% | 2.7% |
Questions
How often are flights from SFO to SEA on time?
71% of 6,824 scheduled flights from San Francisco, CA to Seattle, WA arrived within 15 minutes of schedule between September 2025 and August 2026. 1.1% were cancelled.
What is the best time of day to fly SFO to SEA?
Flights scheduled to leave at 5 a.m. were the most reliable (94% on time). The 8 a.m. departures were the least (58%).
Which airline is most on time from SFO to SEA?
United Airlines: 75% of its 2,336 flights on the route arrived on time. Alaska Airlines: 68%. Delta Air Lines: 73%.
What month has the most delays from SFO to SEA?
June (64% on time). The best month is November (82%), over 2023–2026.
Is the last flight of the day from SFO to SEA more likely to be cancelled?
No, the opposite. Each airline's last SFO–SEA flight of the day was cancelled 0.7% of the time over the past year, against 1.1% for its earlier flights. If the last flight is cancelled, the next one is usually the following morning.
Related
- SEA → SFO (return)
- San Francisco (SFO) delays by hour
- Flights into Seattle-Tacoma (SEA)
- Alaska Airlines on-time record
- United Airlines on-time record
- Delta Air Lines on-time record
- Southwest Airlines on-time record
- Connecting off this flight? Check the risk
Domestic flights by the airlines that report to the U.S. DOT, plus their regional partners. "On time" means arriving less than 15 minutes after schedule; cancelled and diverted flights count as not on time. Past performance is a guide, not a forecast. Method.