Route reliability record
SEA→SJC
Seattle to San Jose
- Flights
- 4,425
- Period
- September 2025 to August 2026
- Distance
- 696 mi
- Carriers
- 6
This route lands a B+, 3 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 roughly 50 minutes on average. That rests on 4,425 SEA to SJC flights, of which SkyWest Airlines flew 1,626 at 85.7% on time.
Best time to fly SEA to SJC: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 91.5% of the time and Wednesday flights 85.4%, against 80.1% for the route overall.
SkyWest Airlines is the most reliable of the three carriers covered here at 85.7% on time across 1,626 flights.
Key figures
On time
80.1%
Arrivals under 15 minutes late, of 4,399 completed flights
Avg delay
49 min
Across delayed arrivals only, not all flights
Cancelled
0.56%
National rate is 1.89%
Best carrier
SkyWest
85.7% on time across 1,626 flights
These figures cover 4,425 flights between September 2025 and August 2026. The median arrival is 5 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.
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Carrier by carrier
Which airline is most reliable on SEA to SJC
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 85.7% of the time; Southwest Airlines manages 70.5%. Sample sizes sit next to every figure, because a two-point gap across 903 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlinesthin sample | 1 | 100.0% | — | 0.00% | A+ |
| Delta Air Linesthin sample | 4 | 100.0% | — | 0.00% | A+ |
| American Airlinesthin sample | 4 | 100.0% | — | 0.00% | A+ |
| SkyWest Airlines | 1,626 | 85.7% | 59 min | 0.18% | A+ |
| Alaska Airlines | 1,887 | 79.8% | 44 min | 1.06% | B |
| Southwest Airlines | 903 | 70.5% | 46 min | 0.22% | C+ |
The spread between SkyWest and Southwest is 15 points, wide enough that it should decide the booking. On a hundred trips that is 15 more arrivals inside the on-time window.
Flight by flight
Flights on SEA to SJC
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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Best ways to make this trip
The most reliable ways to fly Seattle to San Jose
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 2 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. SEA → SJCSeattle to San Jose | SkyWest Airlines | 85.5% | 85.7% | 0.18% | 8am–11am, Tue | OO 3736 08:30 |
| 2. SEA → SJCSeattle to San Jose | Alaska Airlines | 79.0% | 79.8% | 1.06% | 5am–8am, Wed | — |
| 3. SEA → OAKSeattle to Oakland | Alaska Airlines | 77.3% | 78.3% | 1.27% | 5am–8am, Mon | AS 706 21:45 |
| 4. SEA → SJCSeattle to San Jose | Southwest Airlines | 70.3% | 70.5% | 0.22% | 8am–11am, Tue | — |
| 5. SEA → OAKSeattle to Oakland | Southwest Airlines | 69.6% | 69.8% | 0.28% | 5am–8am, Wed | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 18 points, against 15 points between the best and worst carrier.
- 5am–8am399 flights91.5%
- 8am–11am848 flights89.2%
- 11am–2pm911 flights77.0%
- 2pm–5pm869 flights78.8%
- 5pm–8pm706 flights75.2%
- 8pm–5am692 flights73.2%
Scale runs 65% to 95%.
Book the early departure. Flights leaving between 5am–8am arrive on time 91.5% of the time, against 73.2% for the overnight window. That is 18 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 911 flights scheduled in it.
Explore
Filter SEA to SJC 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 SEA to SJC, the best departure window is 5am–8am at 91.5% on time and the worst is 8pm–5am at 73.2%, a wide gap of 18.3 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am91.5%
- 8–11am89.2%
- 11am–2pm77.0%
- 2–5pm78.8%
- 5–8pm75.2%
- 8pm–5am73.2%
best all US flightsScale 60% to 95%.
Across the year
When delays peak on this route
This route's year swings by 22 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.
August is the worst month at 67.2% on time, 22 points below April, the best at 89.5%. 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 438 flights.
Across the week, Wednesday is the strongest day at 85.4% on time and Friday the weakest at 75.4%, a spread of 10 points.
Delay causes
Why this route gets delayed
Carrier accounts for 42% of the 43,000 delay minutes carriers reported here, and the remaining four split what is left.
- 42%Carrier
- 37%Late-arriving aircraft
- 11%National Airspace System
- 9%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. Across 43,000 reported delay minutes here, that single category outweighs weather by 4 to one. The split is drawn from 42,666 reported delay minutes.
The largest share of delay minutes, 42%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 18,000 of the 43,000 delay minutes reported here.
Cancellations are rare at 0.56%, below the national 1.89% 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.
Connections and stage length
What a delay here actually costs
Badly late arrivals are rare here: only 4.7% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
The 696 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.
The return leg runs 82.7% on time across 4,422 flights, within 3 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 4,425 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
Work out the risk of missing a connection in SJC after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. April runs 89.5% on time and August 67.2%, a swing of 22 points. If the dates move at all, move them out of August before you think about anything else. 4,399 completed flights over 12 months sit behind that.
Common questions
SEA to SJC questions
How often is SEA to SJC 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 19.9% of the 4,425 flights in this analysis, against 22.7% nationally. Delayed flights are late by roughly 50 minutes on average.
Which airline is most reliable on SEA to SJC?
SkyWest Airlines leads at 85.7% on time across 1,626 flights. Southwest Airlines is at the other end on 70.5%, a gap of 15 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 SEA to SJC?
The 5am–8am departure window is the strongest at 91.5% on time. The 8pm–5am window is the weakest at 73.2%, 18 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 August delays on SEA to SJC?
August is the weakest month at 67.2% on time, compared with 89.5% in April. Across the year that is 22 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
- SJC to SEA — the return legseparate record
- Seattle-Tacoma International (SEA) delay statistics
- Norman Y. Mineta San Jose International (SJC) delay statistics
- SkyWest Airlines on SEA to SJC85.7%
- Alaska Airlines on SEA to SJC79.8%
- Southwest Airlines on SEA to SJC70.5%
- SEA to LAX, a related route82.0%
- SAN to SJC, a related route74.5%
- SEA to PHX, a related route78.2%
- United Airlines on-time record100.0%
- Delta Air Lines on-time record100.0%
- American Airlines on-time record100.0%
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
Direction matters. SEA to SJC and SJC to SEA are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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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.