Route reliability record

SAN→SJC

San Diego to San Jose

Flights: 4,953
Period: July 2025 to June 2026
Distance: 417 mi
Carriers: 4

This route lands a B+, level with the national rate of 77.6%. Roughly one flight in four 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 4,953 flights, of which SkyWest Airlines flew 1,140 at 82.9% on time.

The US average over the same twelve months is 77.6%, 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.

On time

77.6%

Arrivals under 15 minutes late, of 4,908 completed flights

Avg delay

50 min

Across delayed arrivals only, not all flights

Cancelled

0.87%

National rate is 1.81%

Best carrier

SkyWest

82.9% on time across 1,140 flights

These figures cover 4,953 flights between July 2025 and June 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 choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 82.9% of the time; Southwest Airlines manages 76.0%. Sample sizes sit next to every figure, because a two-point gap across 3,741 flights means less than a ten-point one.

On-time performance by carrier on SAN to SJC
Airline	Flights	On time	Avg delay	Cancelled	Grade
SkyWest Airlines	1,140	82.9%	54 min	1.14%	B
Alaska Airlinesthin sample	48	81.2%	33 min	0.00%	B+
Southwest Airlines	3,741	76.0%	49 min	0.80%	B+
Spirit Airlinesthin sample	24	75.0%	115 min	0.00%	B+

SkyWest leads Southwest by 7 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

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 28 points, against 7 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am461 flights96.3%
8am–11am1,105 flights87.5%
11am–2pm880 flights75.5%
2pm–5pm797 flights68.1%
5pm–8pm1,059 flights72.1%
8pm–5am651 flights70.8%

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 96.3% of the time, against 68.1% for the afternoon window. That is 28 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 1,105 flights scheduled in it.

Across the year

When delays peak on this route

This route's year swings by 19 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.

Darker means more delays. Figures are on-time percentages.January best, June worst

June is the worst month at 67.6% on time, 19 points below January, the best at 86.7%. 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 471 flights.

Across the week, Wednesday is the strongest day at 87.9% on time and Sunday the weakest at 70.0%. 18 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 66% of the 55,000 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.

Late-arriving aircraft
66%
Carrier
25%
National Airspace System
7%
Extreme weather
2%
Security
0%

66% 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 55,000 reported delay minutes here, that single category outweighs weather by 33 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 55,168 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 96.3% on time here.

Cancellations are rare at 0.87%, below the national 1.81% 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

5.8% of arrivals land an hour or more late, close to the national 8.1%. 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 72.4% on time across 4,979 flights, 5 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 5 points of difference.

The sample behind these figures is 4,953 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 June 67.6%, a swing of 19 points. If the dates move at all, move them out of June before you think about anything else. 4,908 completed flights over 12 months sit behind that.

Common questions

SAN to SJC questions

How often is SAN to SJC delayed?

Roughly one flight in four arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 22.4% of the 4,953 flights in this analysis, against 22.4% nationally. Delayed flights are late by about 50 minutes on average.

Which airline is most reliable on SAN to SJC?

SkyWest Airlines leads at 82.9% on time across 1,140 flights. Southwest Airlines is at the other end on 76.0%, a gap of 7 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 96.3% on time. The 2pm–5pm window is the weakest at 68.1%, 28 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 June delays on SAN to SJC?

June is the weakest month at 67.6% on time, compared with 86.7% in January. Across the year that is 19 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.

Where to go next

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, July 2025 to June 2026. Updated monthly. How this data is collected.

Key figures