Airport month record

DENAUG

Denver International in August 2025

Departures: 28,084
Month: August 2025
National, same month: 77.4%
Carriers: 9

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

DEN in August sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 7 points worse than the national rate of 77.4%. The late ones land a little over an hour behind schedule. That rests on 28,084 flights, of which Delta Air Lines flew 1,059 at 80.4% on time.

Delta Air Lines is the most reliable of the six carriers covered here at 80.4% on time across 1,059 flights.

On time

70.1%

Arrivals under 15 minutes late, of 27,781 completed departures

Avg delay

69 min

Across delayed arrivals only, not all flights

Cancelled

0.73%

Nationally in August: 1.08%

Whole year

76.3%

DEN across all twelve months

These figures cover 28,084 departures from Denver International in August 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

August next to DEN's other months

Against DEN's own year, August ran 6 points worse than the twelve-month rate of 76.3%, which makes it number ten of twelve months, best first. Either side of it, July ran 63.0% on time and September 79.4%, so this month sits in line with its neighbours.

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 (this page)	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	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 August

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 39 points, against 15 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am2,103 flights90.1%
8am–11am5,798 flights82.0%
11am–2pm6,057 flights79.4%
2pm–5pm4,283 flights68.0%
5pm–8pm5,987 flights50.8%
8pm–5am3,856 flights58.8%

Scale runs 40% to 95%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 50.8% on time, against 90.1% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 11am–2pm window is the busiest, with 6,057 flights scheduled in it.

Across the week, Tuesday is the strongest day at 78.4% on time and Friday the weakest at 64.7%. 14 points is a smaller lever than departure hour, but it is free.

Carrier by carrier

Which airlines ran best at DEN in August

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 80.4% of the time; Southwest Airlines manages 65.6%. Sample sizes sit next to every figure, because a two-point gap across 7,597 flights means less than a ten-point one.

Carriers at DEN in August 2025
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	9,440	71.2%	68 min	0.78%	C+
Southwest Airlines	7,597	65.6%	60 min	0.41%	C+
SkyWest Airlines	6,751	71.2%	80 min	0.98%	C+
Frontier Airlines	1,982	73.7%	65 min	0.66%	C+
Delta Air Lines	1,059	80.4%	70 min	0.76%	B+
American Airlines	777	70.3%	113 min	1.54%	C
Alaska Airlinesthin sample	253	63.7%	50 min	0.40%	D+
JetBlue Airwaysthin sample	150	75.8%	88 min	0.67%	B+
Allegiant Airthin sample	73	64.4%	119 min	0.00%	D+

The spread between Delta and Southwest is 15 points, wide enough that it should decide the booking. On a hundred trips that is 15 more arrivals inside the on-time window.

Route by route

Busiest routes out of DEN in August

Routes from DEN in August 2025
Route	Flights	On time	Avg delay	Cancelled	Grade
DEN to SLC · Salt Lake City	669	73.5%	70 min	0.75%	C+
DEN to LAX · Los Angeles	658	76.2%	78 min	0.15%	B+
DEN to SEA · Seattle	645	65.2%	56 min	0.62%	C+
DEN to PHX · Phoenix	612	74.6%	77 min	0.65%	C+
DEN to ORD · Chicago	600	65.6%	101 min	1.33%	C
DEN to MSP · Minneapolis	549	72.1%	55 min	0.00%	C+
DEN to LAS · Las Vegas	527	69.5%	59 min	0.76%	C+
DEN to DFW · Dallas-Fort Worth	514	68.7%	107 min	2.72%	C
DEN to ATL · Atlanta	495	78.0%	61 min	0.81%	B+
DEN to COS · Colorado Springs	466	64.0%	78 min	1.07%	D
DEN to SFO · San Francisco	461	69.1%	59 min	0.22%	C+
DEN to PDX · Portland	437	71.6%	55 min	0.00%	C+
DEN to SAN · San Diego	436	69.6%	61 min	0.46%	C+
DEN to LGA · New York	404	72.7%	56 min	0.99%	C+
DEN to IAH · Houston	403	66.8%	65 min	0.50%	C+
DEN to AUS · Austin	399	70.2%	65 min	0.75%	C+
DEN to BOS · Boston	397	72.9%	62 min	0.50%	C+
DEN to MCI · Kansas City	369	69.8%	60 min	0.27%	C+
DEN to MCO · Orlandothin sample	358	68.7%	67 min	1.12%	C
DEN to SMF · Sacramentothin sample	352	75.0%	56 min	1.14%	B
DEN to IAD · Washingtonthin sample	335	71.3%	59 min	0.00%	C+
DEN to BNA · Nashvillethin sample	330	74.1%	53 min	0.61%	C+
DEN to STL · St. Louisthin sample	329	69.9%	64 min	0.61%	C+
DEN to SNA · Santa Anathin sample	311	76.6%	49 min	1.29%	B
DEN to PHL · Philadelphiathin sample	310	67.6%	62 min	0.65%	C+

Delay causes

What held DEN up in August

One category carries most of the weight here. Late-arriving aircraft accounts for 46% of the 576,000 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
46%
Carrier
32%
National Airspace System
17%
Extreme weather
5%
Security
0%

46% 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 576,000 reported delay minutes here, that single category outweighs weather by 10 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 575,639 reported delay minutes.

Cancellations are rare at 0.73%, below the national 1.08% 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.

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 11.0% of arrivals land a full hour or more behind schedule, against 8.2% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.

What to do with this

Flying from DEN in August

For a August trip through DEN: plan on this being one of the airport's harder months. The 5am–8am departures held up best at 90.1% on time, and with 11.0% of arrivals an hour or more late, a connection here deserves more slack than the same trip in November would.

Denver International (DEN), the whole year
DEN in July63.0%
DEN in September79.4%
DEN in October80.8%
DEN in November84.7%
DEN in December74.3%
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