Airport month record

SLCDEC

Salt Lake City International in December 2025

Departures: 9,740
Month: December 2025
National, same month: 73.2%
Carriers: 9

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

SLC in December lands a B+, 11 points better than the national rate of 73.2%. About one flight in six 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 9,740 flights, of which SkyWest Airlines flew 2,990 at 90.2% on time.

SkyWest Airlines is the most reliable of the five carriers covered here at 90.2% on time across 2,990 flights.

On time

83.8%

Arrivals under 15 minutes late, of 9,624 completed departures

Avg delay

64 min

Across delayed arrivals only, not all flights

Cancelled

0.84%

Nationally in December: 1.55%

Whole year

84.8%

SLC across all twelve months

These figures cover 9,740 departures from Salt Lake City International in December 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

December next to SLC's other months

Against SLC's own year, December ran about a point worse than the twelve-month rate of 84.8%, which makes it number ten of twelve months, best first. Either side of it, November ran 86.5% on time and January 85.5%, so a trip moved by a few weeks would have landed in a better 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	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 (this page)	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 December

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 10 points, against 11 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am979 flights89.2%
8am–11am1,844 flights87.2%
11am–2pm1,849 flights81.6%
2pm–5pm1,830 flights81.5%
5pm–8pm1,211 flights78.9%
8pm–5am2,027 flights84.9%

Scale runs 70% to 95%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 89.2% of the time, against 78.9% for the evening window. That is 10 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8pm–5am window is the busiest, with 2,027 flights scheduled in it.

Across the week, Wednesday is the strongest day at 87.8% on time and Friday the weakest at 78.3%. 10 points is a smaller lever than departure hour, but it is free.

Carrier by carrier

Which airlines ran best at SLC in December

The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 90.2% of the time; Southwest Airlines manages 78.9%. Sample sizes sit next to every figure, because a two-point gap across 918 flights means less than a ten-point one.

Carriers at SLC in December 2025
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	4,569	81.4%	59 min	1.09%	B
SkyWest Airlines	2,990	90.2%	68 min	0.43%	A+
Southwest Airlines	918	78.9%	51 min	0.33%	B+
American Airlines	414	82.0%	124 min	0.72%	B+
United Airlines	381	81.5%	65 min	0.26%	B+
Frontier Airlinesthin sample	289	82.7%	56 min	3.11%	B−
Alaska Airlinesthin sample	94	67.7%	44 min	1.06%	C
JetBlue Airwaysthin sample	46	84.1%	55 min	4.35%	B−
Hawaiian Airlinesthin sample	31	61.3%	247 min	0.00%	D+

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 December

Routes from SLC in December 2025
Route	Flights	On time	Avg delay	Cancelled	Grade
SLC to DEN · Denver	623	76.3%	58 min	0.48%	B+
SLC to PHX · Phoenix	514	87.7%	80 min	0.58%	A+
SLC to LAX · Los Angelesthin sample	358	85.5%	48 min	1.68%	A
SLC to DFW · Dallas-Fort Worththin sample	333	81.7%	121 min	1.50%	B
SLC to LAS · Las Vegasthin sample	314	77.2%	57 min	0.96%	B+
SLC to SEA · Seattlethin sample	303	70.7%	53 min	0.33%	C+
SLC to SFO · San Franciscothin sample	295	72.8%	86 min	1.69%	C
SLC to SAN · San Diegothin sample	274	77.8%	60 min	0.73%	B+
SLC to ATL · Atlantathin sample	252	88.0%	51 min	0.40%	A+
SLC to ORD · Chicagothin sample	241	69.5%	71 min	0.41%	C+
SLC to PDX · Portlandthin sample	201	84.4%	56 min	1.00%	B
SLC to IAH · Houstonthin sample	184	88.5%	46 min	1.09%	A
SLC to JFK · New Yorkthin sample	169	83.5%	70 min	2.96%	B
SLC to SMF · Sacramentothin sample	166	81.3%	57 min	0.00%	B+
SLC to SNA · Santa Anathin sample	160	80.6%	38 min	0.62%	B+
SLC to BOI · Boisethin sample	149	83.4%	62 min	2.01%	B
SLC to GEG · Spokanethin sample	147	83.6%	40 min	0.68%	B+
SLC to AUS · Austinthin sample	140	85.7%	61 min	0.00%	A+
SLC to BUR · Burbankthin sample	137	83.6%	54 min	0.00%	B+
SLC to SJC · San Josethin sample	137	86.8%	65 min	0.73%	A+
SLC to MCO · Orlandothin sample	135	79.1%	68 min	0.74%	B+
SLC to LGB · Long Beachthin sample	130	83.7%	44 min	0.77%	B+
SLC to MSP · Minneapolisthin sample	126	83.2%	71 min	0.79%	B+
SLC to DTW · Detroitthin sample	125	89.6%	87 min	0.00%	A+
SLC to OAK · Oaklandthin sample	121	90.1%	28 min	0.00%	A+

Delay causes

What held SLC up in December

One category carries most of the weight here. Carrier accounts for 50% of the 100,000 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
30%
National Airspace System
18%
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 50,000 of the 100,000 delay minutes reported here. The split is drawn from 100,448 reported delay minutes.

Cancellations are rare at 0.84%, below the national 1.55% 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.

5.0% of arrivals land an hour or more late, close to the national 10.0%. 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.

What to do with this

Flying from SLC in December

For a December trip through SLC: plan on this being one of the airport's harder months. The 5am–8am departures held up best at 89.2% on time, and with 5.0% of arrivals an hour or more late, a connection here deserves more slack than the same trip in September would.

Salt Lake City International (SLC), the whole year
SLC in July79.5%
SLC in August84.3%
SLC in September88.2%
SLC in October85.7%
SLC in November86.5%
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