Carrier route record

WNSLC→SMF

Southwest Airlines · Salt Lake City to Sacramento

Flights: 576
Period: July 2025 to June 2026
Share of route: 27%
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 SMF lands a B+, 4 points better than the national rate of 77.6%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 576 flights, with a median arrival 8 minutes early.

Set against the rest of the country, Southwest's SLC to SMF record is 4 points better than the US average of 77.6%. That gap is worth roughly 41 fewer late arrivals for every thousand flights.

On time

81.7%

Arrivals under 15 minutes late, of 574 completed flights

Avg delay

57 min

Across delayed arrivals only, not all flights

Cancelled

0.35%

National rate is 1.81%

Whole route

85.7%

Every carrier on SLC to SMF, 2,158 flights

These figures cover 576 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 SMF

Southwest flew 576 of the 2,158 flights on SLC to SMF, about 27% of it. Its 81.7% on time is 4 points worse than the route as a whole, which runs 85.7%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from Delta at 87.3% to Southwest at 81.7%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.

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 SMF
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	1,509	87.3%	63 min	0.86%	A+
SkyWest Airlinesthin sample	73	84.9%	57 min	0.00%	B+
Southwest Airlines (this page)	576	81.7%	57 min	0.35%	B+

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 32 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–8am132 flights97.0%
8am–11am82 flights86.4%
11am–2pm14 flights—
2pm–5pm61 flights83.3%
5pm–8pm189 flights77.8%
8pm–5am98 flights65.3%

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

Book the early departure. Flights leaving between 5am–8am arrive on time 97.0% of the time, against 65.3% for the overnight window. That is 32 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5pm–8pm window is the busiest, with 189 flights scheduled in it.

Across the year

Southwest on SLC to SMF through the year

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

June is the worst month at 69.6% on time, 21 points below February, the best at 90.7%. 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 57 flights.

Across the week, Tuesday is the strongest day at 85.1% on time and Thursday the weakest at 78.7%. 6 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 83% of the 6,002 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
83%
Carrier
14%
National Airspace System
3%
Extreme weather
0%

83% 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 6,002 reported delay minutes here, that single category outweighs weather by 83 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 6,002 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 97.0% on time here.

Cancellations are rare at 0.35%, 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

6.1% 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 about an hour, which a normal layover absorbs.

The 532 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 runs 81.6% on time across 576 flights, within half a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

One caution: this is a thin sample. 576 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 SMF

Put together: treat all of this as provisional. 576 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 81.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 574 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