Airport month record

DENDEC

Denver International in December 2025

Departures: 26,026
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 DEN, see live FAA status.

DEN in December sits in the middle of the pack with a C+. Close to three flights in four arrive on time by the DOT's definition, about a point better than the national rate of 73.2%. The late ones land a little over an hour behind schedule. That rests on 26,026 flights, of which United Airlines flew 8,548 at 77.8% on time.

United Airlines is the most reliable of the six carriers covered here at 77.8% on time across 8,548 flights.

On time

74.3%

Arrivals under 15 minutes late, of 25,775 completed departures

Avg delay

68 min

Across delayed arrivals only, not all flights

Cancelled

0.64%

Nationally in December: 1.55%

Whole year

76.3%

DEN across all twelve months

These figures cover 26,026 departures from Denver 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 DEN's other months

Against DEN's own year, December ran 2 points worse than the twelve-month rate of 76.3%, which makes it number nine of twelve months, best first. Either side of it, November ran 84.7% on time and January 82.3%, so a trip moved by a few weeks would have landed in a better stretch.

DEN month by month
Month	Flights	On time	Avg delay	Cancelled	Grade
July 2025	29,433	63.0%	77 min	1.48%	D
August 2025	28,084	70.1%	69 min	0.73%	C+
September 2025	26,548	79.4%	54 min	0.12%	B+
October 2025	27,763	80.8%	52 min	0.13%	B+
November 2025	25,280	84.7%	62 min	1.44%	B
December 2025 (this page)	26,026	74.3%	68 min	0.64%	C+
January 2026	24,484	82.3%	60 min	1.69%	B
February 2026	23,046	82.4%	69 min	0.88%	B+
March 2026	27,089	76.8%	72 min	1.50%	B
April 2026	25,345	82.5%	56 min	0.27%	B+
May 2026	27,406	76.4%	58 min	0.28%	B+
June 2026	28,634	67.1%	64 min	0.41%	C+

Departure window

The best time of day to leave DEN in December

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 16 points, against 9 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am2,099 flights85.0%
8am–11am5,333 flights80.5%
11am–2pm5,759 flights74.5%
2pm–5pm3,677 flights70.7%
5pm–8pm5,641 flights69.7%
8pm–5am3,517 flights68.9%

Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 85.0% of the time, against 68.9% for the overnight window. That is 16 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 5,759 flights scheduled in it.

Across the week, Tuesday is the strongest day at 84.3% on time and Friday the weakest at 63.8%. 21 points is a smaller lever than departure hour, but it is free.

Carrier by carrier

Which airlines ran best at DEN in December

The choice of carrier is not cosmetic here. United Airlines arrives on time 77.8% of the time; Southwest Airlines manages 68.4%. Sample sizes sit next to every figure, because a two-point gap across 7,415 flights means less than a ten-point one.

Carriers at DEN in December 2025
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	8,548	77.8%	64 min	0.22%	B+
Southwest Airlines	7,415	68.4%	56 min	0.59%	C+
SkyWest Airlines	6,240	76.7%	89 min	0.88%	B+
Frontier Airlines	1,733	75.7%	63 min	0.81%	B+
Delta Air Lines	996	73.4%	80 min	2.41%	C
American Airlines	723	74.1%	94 min	0.83%	C+
Alaska Airlinesthin sample	204	63.7%	53 min	0.00%	D+
JetBlue Airwaysthin sample	110	72.6%	153 min	3.64%	C−
Envoy Airthin sample	39	64.1%	59 min	0.00%	D+

United leads Southwest by 9 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Route by route

Busiest routes out of DEN in December

Routes from DEN in December 2025
Route	Flights	On time	Avg delay	Cancelled	Grade
DEN to PHX · Phoenix	775	76.1%	63 min	0.52%	B+
DEN to LAX · Los Angeles	651	75.2%	67 min	0.61%	B+
DEN to SLC · Salt Lake City	628	72.0%	62 min	0.32%	C+
DEN to LAS · Las Vegas	560	74.6%	57 min	0.36%	C+
DEN to SAN · San Diego	538	70.7%	59 min	0.56%	C+
DEN to DFW · Dallas-Fort Worth	481	75.1%	62 min	0.00%	B+
DEN to SEA · Seattle	468	59.3%	63 min	0.85%	D+
DEN to ATL · Atlanta	459	74.2%	60 min	1.09%	C
DEN to SFO · San Francisco	457	64.0%	67 min	0.22%	D+
DEN to AUS · Austin	450	78.0%	78 min	0.00%	B+
DEN to COS · Colorado Springs	441	75.9%	81 min	1.13%	B
DEN to MSP · Minneapolis	438	68.3%	67 min	0.46%	C+
DEN to ORD · Chicago	416	69.4%	79 min	0.72%	C+
DEN to MCO · Orlando	403	77.2%	75 min	0.50%	B+
DEN to LGA · New York	391	71.4%	78 min	4.60%	C−
DEN to IAH · Houston	391	82.3%	56 min	0.26%	B+
DEN to PDX · Portlandthin sample	346	66.0%	50 min	0.29%	C+
DEN to MCI · Kansas Citythin sample	336	77.9%	67 min	1.49%	B
DEN to SNA · Santa Anathin sample	316	79.2%	46 min	0.32%	B+
DEN to IAD · Washingtonthin sample	307	85.2%	56 min	0.65%	A+
DEN to SMF · Sacramentothin sample	303	68.6%	64 min	0.00%	C+
DEN to BOS · Bostonthin sample	303	85.7%	58 min	0.66%	A+
DEN to SAT · San Antoniothin sample	282	76.2%	49 min	0.35%	B+
DEN to EWR · Newarkthin sample	281	80.4%	81 min	0.36%	B+
DEN to TPA · Tampathin sample	280	79.4%	84 min	0.36%	B+

Delay causes

What held DEN up in December

One category carries most of the weight here. Late-arriving aircraft accounts for 44% of the 453,000 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.

Late-arriving aircraft
44%
Carrier
34%
National Airspace System
17%
Extreme weather
5%
Security
0%

44% 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 453,000 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 453,042 reported delay minutes.

Cancellations are rare at 0.64%, 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.

8.8% 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 a little over an hour, which a normal layover absorbs.

What to do with this

Flying from DEN in December

For a December trip through DEN: expect 74.3% on time and 0.64% cancelled, going by December 2025. The 5am–8am window was the strongest part of the day.

Denver International (DEN), the whole year
DEN in July63.0%
DEN in August70.1%
DEN in September79.4%
DEN in October80.8%
DEN in November84.7%
DEN in January82.3%
DEN in February82.4%
DEN in March76.8%
DEN in April82.5%
DEN in May76.4%
DEN in June67.1%

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