Carrier route record

WNSLC→SJC

Southwest Airlines · Salt Lake City to San Jose

Flights: 224
Period: July 2025 to June 2026
Share of route: 12%
Carriers: 3

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.

Southwest on SLC to SJC lands a B+, level with the national rate of 77.6%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by roughly 50 minutes on average. That is a workable record, not a spotless one. That rests on 224 flights. The strongest carrier on the route with a full sample, SkyWest Airlines, flew 694 at 92.9% on time.

The US average over the same twelve months is 77.6%, so there is little to separate Southwest on SLC to SJC from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

77.9%

Arrivals under 15 minutes late, of 222 completed flights

Avg delay

48 min

Across delayed arrivals only, not all flights

Cancelled

0.89%

National rate is 1.81%

Whole route

87.0%

Every carrier on SLC to SJC, 1,810 flights

These figures cover 224 flights between July 2025 and June 2026. The median arrival is 7 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

Southwest against every carrier on SLC to SJC

Southwest flew 224 of the 1,810 flights on SLC to SJC, about 12% of it. Its 77.9% on time is 9 points worse than the route as a whole, which runs 87.0%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from SkyWest at 92.9% to Southwest at 77.9%.

The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 92.9% of the time; Delta Air Lines manages 84.6%. Sample sizes sit next to every figure, because a two-point gap across 892 flights means less than a ten-point one.

On-time performance by carrier on SLC to SJC
Airline	Flights	On time	Avg delay	Cancelled	Grade
SkyWest Airlines	694	92.9%	61 min	0.14%	A+
Delta Air Lines	892	84.6%	73 min	0.45%	B+
Southwest Airlines (this page)thin sample	224	77.9%	48 min	0.89%	B+

SkyWest leads Delta by 8 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Departure window

When Southwest runs best on this route

Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 224 flights.

5am–8am—
8am–11am3 flights—
11am–2pm95 flights80.6%
2pm–5pm81 flights75.3%
5pm–8pm45 flights75.6%
8pm–5am—

Scale runs 65% to 85%. Rows with fewer than 30 flights show a dash.

The best window here is not the first bank but the 11am–2pm slot at 80.6% on time, ahead of 2pm–5pm at 75.3%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 11am–2pm window is the busiest, with 95 flights scheduled in it.

Across the year

Southwest on SLC to SJC through the year

Jul–Sep 202573 flights94.4%
Oct–Dec 202554 flights70.4%
Jan–Mar 202645 flights77.8%
Apr–Jun 202652 flights62.7%

Scale runs 55% to 100%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 77.9% on time across 224 flights.

Southwest on SLC to SJC did not run the same all year. Its best quarter was Jul–Sep 2025 at 94.4% on time and its weakest Apr–Jun 2026 at 62.7%, a swing of 32 points on roughly 56 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Across the week, Friday is the strongest day at 78.3% on time and Sunday the weakest at 69.4%. 9 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Southwest runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 84% of the 2,364 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
84%
Carrier
13%
National Airspace System
3%

84% 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 2,364 reported delay minutes here, that single category outweighs weather by 84 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 2,364 reported delay minutes.

Cancellations are rare at 0.89%, 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 costs

5.0% 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 last roughly 50 minutes, which a normal layover absorbs.

The 584 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. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

The return leg is a different operation and performs like one: it runs 83.4% on time across 224 flights, 6 points above 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 6 points of difference.

One caution: this is a thin sample. 224 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.

What to do with this

Booking Southwest on SLC to SJC

Put together: treat all of this as provisional. 224 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 77.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 222 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures