Route reliability record
SJC→SEA
San Jose to Seattle
- Flights
- 4,422
- Period
- September 2025 to August 2026
- Distance
- 696 mi
- Carriers
- 6
This route lands a B+, 5 points better than the national rate of 77.3%. About one flight in six arrives 15 minutes late or worse, and those flights are late by roughly 50 minutes on average. That rests on 4,422 SJC to SEA flights, of which SkyWest Airlines flew 1,627 at 88.7% on time.
Best time to fly SJC to SEA: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 95.5% of the time and Wednesday flights 87.6%, against 82.7% for the route overall.
SkyWest Airlines is the most reliable of the three carriers covered here at 88.7% on time across 1,627 flights.
Key figures
On time
82.7%
Arrivals under 15 minutes late, of 4,393 completed flights
Avg delay
52 min
Across delayed arrivals only, not all flights
Cancelled
0.61%
National rate is 1.89%
Best carrier
SkyWest
88.7% on time across 1,627 flights
These figures cover 4,422 flights between September 2025 and August 2026. The median arrival is 9 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 SJC to SEA
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 88.7% of the time; Southwest Airlines manages 75.6%. Sample sizes sit next to every figure, because a two-point gap across 904 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Linesthin sample | 4 | 100.0% | — | 0.00% | A+ |
| American Airlinesthin sample | 2 | 100.0% | — | 0.00% | A+ |
| United Airlinesthin sample | 1 | 100.0% | — | 0.00% | A+ |
| SkyWest Airlines | 1,627 | 88.7% | 63 min | 0.18% | A+ |
| Alaska Airlines | 1,884 | 80.7% | 51 min | 1.27% | B |
| Southwest Airlines | 904 | 75.6% | 46 min | 0.00% | B+ |
The spread between SkyWest and Southwest is 13 points, wide enough that it should decide the booking. On a hundred trips that is 13 more arrivals inside the on-time window.
Flight by flight
Flights on SJC to SEA
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 San Jose to Seattle
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. SJC → SEASan Jose to Seattle | SkyWest Airlines | 88.5% | 88.7% | 0.18% | 5am–8am, Sat | OO 4041 07:15 |
| 2. OAK → SEAOakland to Seattle | Alaska Airlines | 80.6% | 81.9% | 1.53% | 5am–8am, Sat | AS 705 07:00 |
| 3. SJC → SEASan Jose to Seattle | Alaska Airlines | 79.7% | 80.7% | 1.27% | 5am–8am, Wed | AS 1311 10:19 |
| 4. SFO → SEASan Francisco to Seattle | Delta Air Lines | 78.0% | 79.5% | 1.83% | 5am–8am, Sun | DL 2721 05:55 |
| 5. SJC → SEASan Jose to Seattle | Southwest Airlines | 75.6% | 75.6% | 0.00% | 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 20 points, against 13 points between the best and worst carrier.
- 5am–8am806 flights95.5%
- 8am–11am663 flights75.9%
- 11am–2pm682 flights86.3%
- 2pm–5pm924 flights83.1%
- 5pm–8pm1,013 flights76.1%
- 8pm–5am334 flights75.7%
Scale runs 65% to 100%.
Book the early departure. Flights leaving between 5am–8am arrive on time 95.5% of the time, against 75.7% for the overnight window. That is 20 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5pm–8pm window is the busiest, with 1,013 flights scheduled in it.
Explore
Filter SJC to SEA 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 SJC to SEA, the best departure window is 5am–8am at 95.5% on time and the worst is 8pm–5am at 75.7%, a wide gap of 19.8 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am95.5%
- 8–11am75.9%
- 11am–2pm86.3%
- 2–5pm83.1%
- 5–8pm76.1%
- 8pm–5am75.7%
best all US flightsScale 60% to 100%.
Across the year
When delays peak on this route
This route's year swings by 20 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 73.2% on time, 20 points below February, the best at 92.9%. 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 87.6% on time and Thursday the weakest at 78.0%, a spread of 10 points.
Delay causes
Why this route gets delayed
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 40,000 reported delay minutes.
- 37%Carrier
- 31%Late-arriving aircraft
- 25%National Airspace System
- 7%Extreme weather
- 0%Security
The largest share of delay minutes, 37%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 15,000 of the 40,000 delay minutes reported here. The split is drawn from 39,777 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 95.5% on time here.
Cancellations are rare at 0.61%, 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 4.6% 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 80.1% on time across 4,425 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 4,422 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 SEA 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. February runs 92.9% on time and August 73.2%, a swing of 20 points. If the dates move at all, move them out of August before you think about anything else. 4,393 completed flights over 12 months sit behind that.
Common questions
SJC to SEA questions
How often is SJC to SEA delayed?
About one flight in six arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 17.3% of the 4,422 flights in this analysis, against 22.7% nationally. Delayed flights are late by roughly 50 minutes on average.
Which airline is most reliable on SJC to SEA?
SkyWest Airlines leads at 88.7% on time across 1,627 flights. Southwest Airlines is at the other end on 75.6%, a gap of 13 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 SJC to SEA?
The 5am–8am departure window is the strongest at 95.5% on time. The 8pm–5am window is the weakest at 75.7%, 20 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 SJC to SEA?
August is the weakest month at 73.2% on time, compared with 92.9% in February. Across the year that is 20 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 SJC — the return legseparate record
- Norman Y. Mineta San Jose International (SJC) delay statistics
- Seattle-Tacoma International (SEA) delay statistics
- SkyWest Airlines on SJC to SEA88.7%
- Alaska Airlines on SJC to SEA80.7%
- Southwest Airlines on SJC to SEA75.6%
- SJC to SAN, a related route68.3%
- LAX to SEA, a related route85.0%
- SJC to LAX, a related route85.0%
- Delta Air Lines on-time record100.0%
- American Airlines on-time record100.0%
- United Airlines on-time record100.0%
- Same route, different airline: where the carrier you pick matters most
- The best time of day to fly, according to 7.05 million flight records
Direction matters. SJC to SEA and SEA to SJC 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.