Airport month record

IAHDEC

George Bush Intercontinental in December 2025

Departures: 9,971
Month: December 2025
National, same month: 73.2%
Carriers: 10

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

IAH in December lands a B+, 6 points better than the national rate of 73.2%. About one flight in five arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 9,971 flights, of which United Airlines flew 6,317 at 82.3% on time.

United Airlines is the most reliable of the five carriers covered here at 82.3% on time across 6,317 flights.

On time

79.4%

Arrivals under 15 minutes late, of 9,891 completed departures

Avg delay

71 min

Across delayed arrivals only, not all flights

Cancelled

0.60%

Nationally in December: 1.55%

Whole year

78.4%

IAH across all twelve months

These figures cover 9,971 departures from George Bush Intercontinental 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 IAH's other months

Against IAH's own year, December ran about a point better than the twelve-month rate of 78.4%, which makes it number six of twelve months, best first. Cancellations were unusually low for IAH in December, at 0.60% against 1.14% across the year. Either side of it, November ran 78.2% on time and January 85.7%, so a trip moved by a few weeks would have landed in a better stretch.

IAH month by month
Month	Flights	On time	Avg delay	Cancelled	Grade
July 2025	10,311	68.8%	88 min	1.74%	C
August 2025	9,889	74.1%	74 min	0.87%	C+
September 2025	9,493	85.6%	69 min	0.20%	A+
October 2025	10,247	80.7%	65 min	0.30%	B+
November 2025	10,022	78.2%	73 min	1.06%	B
December 2025 (this page)	9,971	79.4%	71 min	0.60%	B+
January 2026	9,656	85.7%	74 min	3.07%	A−
February 2026	8,976	85.6%	68 min	1.06%	A
March 2026	10,492	76.4%	95 min	2.89%	B
April 2026	10,022	80.4%	69 min	0.57%	B+
May 2026	10,105	77.1%	73 min	0.46%	B+
June 2026	9,903	69.9%	79 min	0.75%	C+

Departure window

The best time of day to leave IAH in December

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 17 points, against 11 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am1,651 flights89.0%
8am–11am1,447 flights80.1%
11am–2pm1,577 flights78.5%
2pm–5pm1,765 flights79.9%
5pm–8pm1,813 flights72.0%
8pm–5am1,718 flights77.6%

Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 89.0% of the time, against 72.0% for the evening window. That is 17 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5pm–8pm window is the busiest, with 1,813 flights scheduled in it.

Across the week, Tuesday is the strongest day at 84.9% on time and Sunday the weakest at 66.7%. 18 points is a smaller lever than departure hour, but it is free.

Carrier by carrier

Which airlines ran best at IAH in December

The choice of carrier is not cosmetic here. United Airlines arrives on time 82.3% of the time; Spirit Airlines manages 71.3%. Sample sizes sit next to every figure, because a two-point gap across 524 flights means less than a ten-point one.

Carriers at IAH in December 2025
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	6,317	82.3%	51 min	0.09%	B+
SkyWest Airlines	1,079	74.5%	108 min	0.37%	C+
Delta Air Lines	700	73.4%	89 min	4.57%	C−
American Airlines	612	79.9%	118 min	0.49%	B+
Spirit Airlines	524	71.3%	75 min	1.53%	C
Frontier Airlinesthin sample	362	67.2%	90 min	0.55%	C+
Republic Airwaysthin sample	126	72.1%	102 min	3.17%	C−
Envoy Airthin sample	108	86.1%	34 min	0.00%	A+
Alaska Airlinesthin sample	92	69.6%	48 min	0.00%	C+
JetBlue Airwaysthin sample	42	78.6%	148 min	0.00%	B+

Delta Air Lines cancels 4.6% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.

Route by route

Busiest routes out of IAH in December

Routes from IAH in December 2025
Route	Flights	On time	Avg delay	Cancelled	Grade
IAH to ORD · Chicago	512	74.8%	70 min	0.59%	C+
IAH to DFW · Dallas-Fort Worth	499	75.1%	67 min	0.20%	B+
IAH to LAX · Los Angeles	448	84.0%	61 min	0.67%	B+
IAH to DEN · Denver	390	84.4%	59 min	0.00%	B+
IAH to ATL · Atlanta	367	78.1%	67 min	3.00%	B
IAH to LGA · New Yorkthin sample	348	65.4%	79 min	4.31%	C−
IAH to MIA · Miamithin sample	339	82.5%	73 min	0.29%	B+
IAH to EWR · Newarkthin sample	334	72.7%	54 min	0.30%	C+
IAH to MCO · Orlandothin sample	319	83.6%	89 min	0.63%	B+
IAH to SFO · San Franciscothin sample	311	79.7%	66 min	0.32%	B+
IAH to LAS · Las Vegasthin sample	307	90.2%	94 min	0.00%	A+
IAH to FLL · Fort Lauderdalethin sample	283	79.2%	73 min	0.00%	B+
IAH to DCA · Washingtonthin sample	273	83.0%	67 min	0.73%	B+
IAH to PHX · Phoenixthin sample	270	87.4%	121 min	0.00%	A+
IAH to AUS · Austinthin sample	231	80.1%	44 min	0.00%	B+
IAH to MSY · New Orleansthin sample	224	87.1%	47 min	0.00%	A+
IAH to SAT · San Antoniothin sample	217	83.9%	41 min	0.00%	B+
IAH to SLC · Salt Lake Citythin sample	185	81.0%	76 min	0.54%	B+
IAH to BOS · Bostonthin sample	175	86.3%	85 min	0.00%	A+
IAH to SEA · Seattlethin sample	169	70.7%	42 min	0.00%	C+
IAH to DTW · Detroitthin sample	169	79.5%	74 min	1.78%	B
IAH to CLT · Charlottethin sample	168	85.1%	51 min	0.00%	A+
IAH to PHL · Philadelphiathin sample	157	85.7%	96 min	1.91%	A
IAH to TPA · Tampathin sample	150	83.3%	53 min	0.00%	B+
IAH to MSP · Minneapolisthin sample	145	68.1%	86 min	2.76%	C

Delay causes

What held IAH up in December

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 145,000 reported delay minutes.

Carrier
40%
Late-arriving aircraft
37%
National Airspace System
22%
Extreme weather
1%
Security
0%

37% 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 145,000 reported delay minutes here, that single category outweighs weather by 28 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 145,063 reported delay minutes.

Cancellations are rare at 0.60%, 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.

6.9% 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 IAH in December

For a December trip through IAH: expect 79.4% on time and 0.60% cancelled, going by December 2025. The 5am–8am window was the strongest part of the day.

George Bush Intercontinental (IAH), the whole year
IAH in July68.8%
IAH in August74.1%
IAH in September85.6%
IAH in October80.7%
IAH in November78.2%
IAH in January85.7%
IAH in February85.6%
IAH in March76.4%
IAH in April80.4%
IAH in May77.1%
IAH in June69.9%

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