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DelayAtlas

Carrier route record

WNSLC→SJC

Southwest Airlines · Salt Lake City to San Jose

Flights
208
Period
September 2025 to August 2026
Share of route
12%
Carriers
3
C+GRADE

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

Southwest on SLC to SJC sits in the middle of the pack with a C+. Close to three flights in four arrive on time by the DOT's definition, 3 points worse than the national rate of 77.3%. The late ones land roughly 45 minutes behind schedule. That rests on 208 flights. The strongest carrier on the route with a full sample, SkyWest Airlines, flew 664 at 92.0% on time.

The US average over the same twelve months is 77.3%, 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.

Key figures

On time

74.3%

Arrivals under 15 minutes late, of 206 completed flights

Avg delay

44 min

Across delayed arrivals only, not all flights

Cancelled

0.96%

National rate is 1.89%

Whole route

86.7%

Every carrier on SLC to SJC, 1,796 flights

These figures cover 208 flights between September 2025 and August 2026. The median arrival is 4 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

Southwest against every carrier on SLC to SJC

Southwest flew 208 of the 1,796 flights on SLC to SJC, about 12% of it. Its 74.3% on time is 12 points worse than the route as a whole, which runs 86.7%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from SkyWest at 92.0% to Southwest at 74.3%.

The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 92.0% of the time; Delta Air Lines manages 85.7%. Sample sizes sit next to every figure, because a two-point gap across 924 flights means less than a ten-point one.

On-time performance by carrier on SLC to SJC
AirlineFlightsOn timeAvg delayCancelledGrade
SkyWest Airlines66492.0%75 min0.15%A+
Delta Air Lines92485.7%70 min0.43%A+
Southwest Airlines (this page)thin sample20874.3%44 min0.96%C+

SkyWest leads Delta by 6 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.

Departure window

When Southwest runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 14 points, against 6 points between the best and worst carrier.

  • 5am–8am—
  • 8am–11am3 flights—
  • 11am–2pm97 flights77.9%
  • 2pm–5pm64 flights75.0%
  • 5pm–8pm44 flights63.6%
  • 8pm–5am—

Scale runs 55% to 85%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 63.6% on time, against 77.9% for the 11am–2pm slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 11am–2pm window is the busiest, with 97 flights scheduled in it.

Across the year

Southwest on SLC to SJC through the year

  • Jul–Sep 202521 flights—
  • Oct–Dec 202554 flights70.4%
  • Jan–Mar 202645 flights77.8%
  • Apr–Jun 202652 flights62.7%
  • Jul–Sep 202636 flights77.8%

Scale runs 55% to 85%. 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 74.3% on time across 208 flights.

Southwest on SLC to SJC did not run the same all year. Its best quarter was Jan–Mar 2026 at 77.8% on time and its weakest Apr–Jun 2026 at 62.7%, a swing of 15 points on roughly 52 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, Monday is the strongest day at 80.4% on time and Sunday the weakest at 62.0%, a spread of 18 points.

Arrival by arrival

How late Southwest on SLC to SJC runs when it is late

Southwest on SLC to SJC often beats the schedule: 54 of 206 completed flights, 26%, arrived 15 minutes or more early. The 53 late arrivals split 25 under half an hour, 19 between 30 and 60 minutes, and 9 an hour or more.

  • 15+ min early54 flights26.2%
  • Within 15 min99 flights48.1%
  • 15–29 min late25 flights12.1%
  • 30–59 min late19 flights9.2%
  • 1–2 hours late6 flights2.9%
  • 2+ hours late3 flights1.5%

Scale runs 0% to 100%.

Share of 206 completed flights by arrival against schedule.

A late pushback is often recovered here: of 70 departures that left 15 minutes late or more, 21 still arrived on time. Only 4 left on time and still arrived late.

The worst days

Worst days for Southwest on SLC to SJC

The latest arrival of the period was on 20 April 2026, 3 hours 38 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on five of the five worst days.

The latest arrivals of Southwest on SLC to SJC in the period
DateArrived late byLargest filed cause
20 April 20263 hours 38 minutesLate-arriving aircraft
8 March 20262 hours 30 minutesLate-arriving aircraft
19 June 20262 hours 10 minutesLate-arriving aircraft
1 November 20251 hour 57 minutesLate-arriving aircraft
9 November 20251 hour 35 minutesLate-arriving aircraft

Delay causes

Why Southwest runs late on this route

Late-arriving aircraft accounts for 81% of the 2,310 delay minutes carriers reported here, and the remaining four split what is left.

  • Late-arriving aircraft
    81%
  • Carrier
    15%
  • National Airspace System
    4%

81% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 2,310 reported delay minutes here, that single category outweighs weather by 81 to one. The split is drawn from 2,310 reported delay minutes.

Cancellations sit at 0.96% against a national 1.89%, which is ordinary. Diversions add another 0.00%.

Connections and stage length

What a delay here costs

Badly late arrivals are rare here: only 4.4% 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 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.

The return leg is a different operation and performs like one: it runs 78.7% on time across 208 flights, 4 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 4 points of difference.

One caution: this is a thin sample. 208 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. 208 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 74.3% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 206 completed flights over 12 months sit behind that.

Related

Where to go next

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.