Airport month record

SLCSEP

Salt Lake City International in September 2025

Departures: 9,344
Month: September 2025
National, same month: 83.4%
Carriers: 10

Historical statistics for September 2025, not live status or a forecast for this year’s September. For today’s conditions at SLC, see live FAA status.

SLC in September earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 5 points better than the national rate of 83.4%. When something does go wrong the average delay runs about an hour. That rests on 9,344 flights, of which SkyWest Airlines flew 2,850 at 94.4% on time.

SkyWest Airlines is the most reliable of the four carriers covered here at 94.4% on time across 2,850 flights.

On time

88.2%

Arrivals under 15 minutes late, of 9,309 completed departures

Avg delay

62 min

Across delayed arrivals only, not all flights

Cancelled

0.19%

Nationally in September: 0.51%

Whole year

84.8%

SLC across all twelve months

These figures cover 9,344 departures from Salt Lake City International in September 2025. On time means an arrival less than 15 minutes after the scheduled gate time, the DOT's threshold, and the national comparison uses every US departure in the same month rather than the whole year.

Against the year

September next to SLC's other months

Against SLC's own year, September ran 3 points better than the twelve-month rate of 84.8%, which makes it the best of the twelve months in the data. Cancellations were unusually low for SLC in September, at 0.19% against 0.76% across the year. Either side of it, August ran 84.3% on time and October 85.7%, so a trip moved by a few weeks would have landed in a worse stretch.

SLC month by month
Month	Flights	On time	Avg delay	Cancelled	Grade
July 2025	10,346	79.5%	69 min	0.67%	B+
August 2025	9,985	84.3%	62 min	0.39%	B+
September 2025 (this page)	9,344	88.2%	62 min	0.19%	A+
October 2025	9,841	85.7%	60 min	0.11%	A+
November 2025	9,197	86.5%	71 min	1.72%	A
December 2025	9,740	83.8%	64 min	0.84%	B+
January 2026	9,515	85.5%	66 min	1.79%	A
February 2026	9,167	85.5%	73 min	0.99%	A+
March 2026	10,632	85.8%	67 min	1.21%	A
April 2026	9,877	84.4%	60 min	0.38%	B+
May 2026	10,146	85.3%	57 min	0.42%	A+
June 2026	10,084	83.3%	64 min	0.48%	B+

Departure window

The best time of day to leave SLC in September

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 9,344 flights.

5am–8am688 flights92.4%
8am–11am1,933 flights90.8%
11am–2pm1,983 flights89.2%
2pm–5pm1,568 flights84.5%
5pm–8pm1,239 flights84.4%
8pm–5am1,933 flights88.4%

Scale runs 75% to 100%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 92.4% of the time, against 84.4% for the evening window. That is 8 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 1,983 flights scheduled in it.

Across the week, Wednesday is the strongest day at 92.4% on time and Thursday the weakest at 83.0%. 9 points is a smaller lever than departure hour, but it is free.

Carrier by carrier

Which airlines ran best at SLC in September

The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 94.4% of the time; Southwest Airlines manages 83.2%. Sample sizes sit next to every figure, because a two-point gap across 896 flights means less than a ten-point one.

Carriers at SLC in September 2025
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	4,393	87.2%	59 min	0.14%	A+
SkyWest Airlines	2,850	94.4%	56 min	0.04%	A+
Southwest Airlines	896	83.2%	51 min	0.22%	B+
United Airlines	374	84.7%	55 min	0.27%	B+
American Airlinesthin sample	287	77.3%	112 min	1.05%	B
Frontier Airlinesthin sample	260	74.3%	100 min	0.77%	C+
Alaska Airlinesthin sample	133	81.1%	41 min	0.75%	B+
Spirit Airlinesthin sample	65	79.4%	67 min	3.08%	B−
JetBlue Airwaysthin sample	32	87.5%	43 min	0.00%	A+
Hawaiian Airlinesthin sample	30	90.0%	21 min	0.00%	A+

SkyWest leads Southwest by 11 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Route by route

Busiest routes out of SLC in September

Routes from SLC in September 2025
Route	Flights	On time	Avg delay	Cancelled	Grade
SLC to DEN · Denver	644	80.5%	58 min	0.16%	B+
SLC to PHX · Phoenix	413	87.8%	74 min	0.24%	A+
SLC to SEA · Seattle	398	82.1%	52 min	0.25%	B+
SLC to LAX · Los Angelesthin sample	338	84.5%	58 min	0.59%	B+
SLC to LAS · Las Vegasthin sample	314	76.9%	66 min	0.64%	B+
SLC to DFW · Dallas-Fort Worththin sample	308	81.5%	121 min	0.97%	B+
SLC to SFO · San Franciscothin sample	250	80.4%	54 min	0.00%	B+
SLC to ORD · Chicagothin sample	244	81.5%	53 min	0.41%	B+
SLC to ATL · Atlantathin sample	241	91.3%	61 min	0.00%	A+
SLC to SMF · Sacramentothin sample	180	90.6%	56 min	0.00%	A+
SLC to SAN · San Diegothin sample	180	88.7%	58 min	1.11%	A
SLC to PDX · Portlandthin sample	176	92.6%	58 min	0.00%	A+
SLC to IAH · Houstonthin sample	161	91.3%	118 min	0.00%	A+
SLC to SJC · San Josethin sample	158	89.8%	86 min	0.63%	A+
SLC to JFK · New Yorkthin sample	150	91.3%	37 min	0.00%	A+
SLC to BOI · Boisethin sample	150	87.3%	57 min	0.00%	A+
SLC to SGU · St. Georgethin sample	146	95.9%	73 min	0.00%	A+
SLC to SNA · Santa Anathin sample	146	82.9%	128 min	0.00%	B+
SLC to OAK · Oaklandthin sample	146	96.6%	51 min	0.00%	A+
SLC to GEG · Spokanethin sample	137	86.9%	130 min	0.00%	A+
SLC to AUS · Austinthin sample	133	88.0%	52 min	0.00%	A+
SLC to BUR · Burbankthin sample	130	89.2%	57 min	0.00%	A+
SLC to MCO · Orlandothin sample	127	88.2%	39 min	0.00%	A+
SLC to LGB · Long Beachthin sample	124	97.6%	32 min	0.00%	A+
SLC to DTW · Detroitthin sample	122	90.2%	81 min	0.00%	A+

Delay causes

What held SLC up in September

One category carries most of the weight here. Carrier accounts for 50% of the 69,000 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.

Carrier
50%
Late-arriving aircraft
27%
National Airspace System
21%
Extreme weather
3%
Security
0%

The largest share of delay minutes, 50%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 34,000 of the 69,000 delay minutes reported here. The split is drawn from 68,661 reported delay minutes.

Cancellations are rare at 0.19%, below the national 0.51% 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.

Badly late arrivals are rare here: only 3.3% land an hour or more behind schedule, against 5.4% 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.

What to do with this

Flying from SLC in September

For a September trip through SLC: this is one of the better months to be flying from here, 88.2% on time with 0.19% cancelled. That is a base rate for the month as a whole; a single storm can still spoil a particular day.

Salt Lake City International (SLC), the whole year
SLC in July79.5%
SLC in August84.3%
SLC in October85.7%
SLC in November86.5%
SLC in December83.8%
SLC in January85.5%
SLC in February85.5%
SLC in March85.8%
SLC in April84.4%
SLC in May85.3%
SLC in June83.3%

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