Route reliability record
SAN→SJC
San Diego to San Jose
- Flights
- 4,980
- Period
- June 2025 to May 2026
- Distance
- 417 mi
- Carriers
- 4
This route lands a B+, about a point better than the national rate of 77.4%. Roughly one flight in five arrive 15 minutes late or worse, and those flights are late by about 50 minutes on average. That is a workable record, not a spotless one. That rests on 4,980 flights, of which SkyWest Airlines flew 1,170 at 81.8% on time.
The US average over the same twelve months is 77.4%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
78.2%
Arrivals under 15 minutes late, of 4,933 completed flights
Avg delay
51 min
Across delayed arrivals only, not all flights
Cancelled
0.90%
National rate is 1.80%
Best carrier
SkyWest
81.8% on time across 1,170 flights
These figures cover 4,980 flights between June 2025 and May 2026. The median arrival is 6 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.
Carrier by carrier
Which airline is most reliable on SAN to SJC
The two carriers here are closely matched: 5 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 1,170 | 81.8% | 54 min | 1.20% | B |
| Southwest Airlines | 3,748 | 77.2% | 50 min | 0.83% | B+ |
| Alaska Airlinesthin sample | 19 | 73.7% | 36 min | 0.00% | C+ |
| Spirit Airlinesthin sample | 43 | 72.1% | 83 min | 0.00% | C+ |
No carrier stands out. SkyWest tops the table at 81.8%, 5 points clear of the bottom, which is inside the range this kind of sample moves year to year.
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 27 points, against 5 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am453 flights96.0%
- 8am–11am1,106 flights87.5%
- 11am–2pm933 flights75.4%
- 2pm–5pm786 flights69.5%
- 5pm–8pm1,050 flights73.8%
- 8pm–5am652 flights71.7%
Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 96.0% of the time, against 69.5% for the afternoon window. That is 27 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on.
Across the year
When delays peak on this route
This route's year swings by 15 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.
Delays peak in May, when the on-time rate falls to 71.9%. January is the strongest month at 86.7%. Moving a flexible trip across that boundary buys 15 points.
Across the week, Wednesday is the strongest day at 87.9% on time and Sunday the weakest at 71.5%. 16 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Late-arriving aircraft accounts for 65% of the 54,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 65%Late-arriving aircraft
- 24%Carrier
- 9%National Airspace System
- 2%Extreme weather
- 1%Security
65% 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 54,000 reported delay minutes here, that single category outweighs weather by 32 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 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 96.0% on time here.
Cancellations sit at 0.90% against a national 1.80%, which is ordinary. Diversions add another 0.04%.
Connections and stage length
What a delay here actually costs
5.7% of arrivals land an hour or more late, close to the national 8.2%. 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 are the about 50 minutes kind, which a normal layover absorbs.
At 417 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 5am–8am window matters as much as it does.
The return leg is a different operation and performs like one: it runs 73.8% on time across 4,990 flights, 4 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 4 points of difference.
The sample behind these figures is 4,980 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.
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 86.7% on time and May 71.9%, a swing of 15 points. If the dates move at all, move them out of May before you think about anything else.
Common questions
SAN to SJC questions
How often is SAN to SJC delayed?
Roughly one flight in five arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 21.8% of the 4,980 flights in this analysis, against 22.6% nationally. Delayed flights are late by about 50 minutes on average.
Which airline is most reliable on SAN to SJC?
SkyWest Airlines leads at 81.8% on time across 1,170 flights. Southwest Airlines is at the other end on 77.2%, a gap of 5 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 SAN to SJC?
The 5am–8am departure window is the strongest at 96.0% on time. The 2pm–5pm window is the weakest at 69.5%, 27 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 May delays on SAN to SJC?
May is the weakest month at 71.9% on time, compared with 86.7% in January. Across the year that is 15 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 SAN — the return legseparate record
- San Diego International (SAN) delay statistics
- Norman Y. Mineta San Jose International (SJC) delay statistics
- SkyWest Airlines on-time record81.8%
- Southwest Airlines on-time record77.2%
- Alaska Airlines on-time record73.7%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Direction matters. SAN to SJC and SJC to SAN are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, June 2025 to May 2026. Updated monthly. How this data is collected.