Route reliability record

SLC→SAN

Salt Lake City to San Diego

Flights: 3,097
Period: September 2025 to August 2026
Distance: 626 mi
Carriers: 5

This route lands a B+, 4 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by roughly 55 minutes on average. That rests on 3,097 SLC to SAN flights, of which Delta Air Lines flew 1,738 at 82.2% on time.

Best time to fly SLC to SAN: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 93.3% of the time and Tuesday flights 85.9%, against 80.9% for the route overall.

Delta Air Lines is the most reliable of the three carriers covered here at 82.2% on time across 1,738 flights.

On time

80.9%

Arrivals under 15 minutes late, of 3,059 completed flights

Avg delay

54 min

Across delayed arrivals only, not all flights

Cancelled

0.90%

National rate is 1.89%

Best carrier

Delta

82.2% on time across 1,738 flights

These figures cover 3,097 flights between September 2025 and August 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.

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Carrier by carrier

Which airline is most reliable on SLC to SAN

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 82.2% of the time; Southwest Airlines manages 72.5%. Sample sizes sit next to every figure, because a two-point gap across 436 flights means less than a ten-point one.

On-time performance by carrier on SLC to SAN
Airline	Flights	On time	Avg delay	Cancelled	Grade
Alaska Airlinesthin sample	1	100.0%	—	0.00%	A+
Frontier Airlinesthin sample	107	83.7%	56 min	2.80%	B
Delta Air Lines	1,738	82.2%	54 min	0.92%	B+
SkyWest Airlines	815	82.2%	57 min	0.86%	B+
Southwest Airlines	436	72.5%	48 min	0.46%	C+

Delta leads Southwest by 10 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Flight by flight

Flights on SLC to SAN

The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.

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Best ways to make this trip

The most reliable ways to fly Salt Lake City to San Diego

Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.

Most reliable ways to fly from SLC to SAN
Option	Airline	Success	On time	Cancelled	Best departure	Most punctual flight
1. SLC → SANSalt Lake City to San Diego	SkyWest Airlines	81.5%	82.2%	0.86%	5am–8am, Tue	OO 3018 07:40
2. SLC → SANSalt Lake City to San Diego	Delta Air Lines	81.4%	82.2%	0.92%	5am–8am, Wed	DL 1177 07:45
3. SLC → SANSalt Lake City to San Diego	Southwest Airlines	72.2%	72.5%	0.46%	5am–8am, Sat	—

Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.

Plan this trip by month, day and time

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 21 points, against 10 points between the best and worst carrier.

5am–8am634 flights93.3%
8am–11am326 flights83.2%
11am–2pm576 flights79.4%
2pm–5pm635 flights71.9%
5pm–8pm548 flights76.8%
8pm–5am378 flights81.2%

Scale runs 65% to 100%.

Book the early departure. Flights leaving between 5am–8am arrive on time 93.3% of the time, against 71.9% for the afternoon window. That is 21 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 2pm–5pm window is the busiest, with 635 flights scheduled in it.

Explore

Filter SLC to SAN by airline, time, month and day

Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.

On SLC to SAN, the best departure window is 5am–8am at 93.3% on time and the worst is 2pm–5pm at 71.9%, a wide gap of 21.4 points. All US flights leaving 5am–8am ran 89.3%.

5–8am93.3%
8–11am83.2%
11am–2pm79.4%
2–5pm71.9%
5–8pm76.8%
8pm–5am81.2%

best all US flightsScale 60% to 100%.

Across the year

When delays peak on this route

This route's year swings by 25 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.March best, August worst

August is the worst month at 66.0% on time, 25 points below March, the best at 91.0%. 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. August was the busiest month here, with 297 flights.

Across the week, Tuesday is the strongest day at 85.9% on time and Friday the weakest at 75.0%, a spread of 11 points.

Delay causes

Why this route gets delayed

Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 31,000 reported delay minutes.

Carrier
34%
National Airspace System
30%
Late-arriving aircraft
29%
Extreme weather
6%

The largest share of delay minutes, 34%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 11,000 of the 31,000 delay minutes reported here. The split is drawn from 31,441 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 93.3% on time here.

Cancellations sit at 0.90% against a national 1.89%, which is ordinary. Diversions add another 0.32%.

Connections and stage length

What a delay here actually costs

Badly late arrivals are rare here: only 4.8% 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 626 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 runs 83.0% on time across 3,100 flights, within 2 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

The sample behind these figures is 3,097 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.

Work out the risk of missing a connection in SAN after this flight

What to do with this

Booking this route

Put together: the calendar is the biggest lever here, not the carrier or the hour. March runs 91.0% on time and August 66.0%, a swing of 25 points. If the dates move at all, move them out of August before you think about anything else. 3,059 completed flights over 12 months sit behind that.

Common questions

SLC to SAN questions

How often is SLC to SAN delayed?

About one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 19.1% of the 3,097 flights in this analysis, against 22.7% nationally. Delayed flights are late by roughly 55 minutes on average.

Which airline is most reliable on SLC to SAN?

Delta Air Lines leads at 82.2% on time across 1,738 flights. Southwest Airlines is at the other end on 72.5%, a gap of 10 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 SLC to SAN?

The 5am–8am departure window is the strongest at 93.3% on time. The 2pm–5pm window is the weakest at 71.9%, 21 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 August delays on SLC to SAN?

August is the weakest month at 66.0% on time, compared with 91.0% in March. Across the year that is 25 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. SLC to SAN and SAN to SLC are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.

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<iframe src="https://delayatlas.com/embed/route/slc-san" width="320" height="132" style="border:0;max-width:100%" loading="lazy" title="SLC to SAN on-time record"></iframe>
<p style="font:12px/1.4 sans-serif;margin:4px 0 0">SLC to SAN flight delay statistics from <a href="https://delayatlas.com/routes/slc-to-san">DelayAtlas</a></p>

Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.