Carrier route record

WNSLC→OAK

Southwest Airlines · Salt Lake City to Oakland

Flights: 596
Period: July 2025 to June 2026
Share of route: 36%
Carriers: 2

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

Southwest on SLC to OAK earns an A+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 9 points better than the national rate of 77.6%. When something does go wrong the average delay runs roughly 50 minutes. That rests on 596 flights, with a median arrival 8 minutes early.

Set against the rest of the country, Southwest's SLC to OAK record is 9 points better than the US average of 77.6%. That gap is worth roughly 86 fewer late arrivals for every thousand flights.

On time

86.2%

Arrivals under 15 minutes late, of 595 completed flights

Avg delay

52 min

Across delayed arrivals only, not all flights

Cancelled

0.17%

National rate is 1.81%

Whole route

90.2%

Every carrier on SLC to OAK, 1,670 flights

These figures cover 596 flights between July 2025 and June 2026. The median arrival is 8 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 OAK

Southwest flew 596 of the 1,670 flights on SLC to OAK, about 36% of it. Its 86.2% on time is 4 points worse than the route as a whole, which runs 90.2%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from SkyWest at 92.4% to Southwest at 86.2%.

Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.

On-time performance by carrier on SLC to OAK
Airline	Flights	On time	Avg delay	Cancelled	Grade
SkyWest Airlines	1,074	92.4%	53 min	0.19%	A+
Southwest Airlines (this page)	596	86.2%	52 min	0.17%	A+

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 27 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am103 flights98.0%
8am–11am124 flights89.5%
11am–2pm156 flights89.7%
2pm–5pm29 flights—
5pm–8pm100 flights75.0%
8pm–5am84 flights71.4%

Scale runs 65% to 100%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 98.0% of the time, against 71.4% for the overnight 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. The 11am–2pm window is the busiest, with 156 flights scheduled in it.

Across the year

Southwest on SLC to OAK through the year

Darker means more delays. Figures are on-time percentages.September best, April worst

September is the best month on the calendar at 96.4% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. February was the busiest month here, with 70 flights.

Across the week, Tuesday is the strongest day at 91.4% on time and Thursday the weakest at 78.1%. 13 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 62% of the 4,271 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
62%
Carrier
27%
Extreme weather
7%
National Airspace System
5%

62% 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 4,271 reported delay minutes here, that single category outweighs weather by 9 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 4,271 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 98.0% on time here.

Cancellations are rare at 0.17%, 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

Badly late arrivals are rare here: only 3.7% land an hour or more behind schedule, against 8.1% 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 588 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 79.5% on time across 596 flights, 7 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 7 points of difference.

One caution: this is a thin sample. 596 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 OAK

Put together: treat all of this as provisional. 596 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 86.2% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 595 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