Guide
Flying in December: the whole month, not just the holidays
December 2025 ran 73.2% on time against 77.3% for the year. Chicago (ORD) fell to 61.0% while Salt Lake City (SLC) held 83.8%. The map explains it.
December is the second of the two bad seasons in US flying, and it is usually blamed on Christmas. The data does not support that. December 2025 ran 73.2% on time, against 77.3% for the full year from September 2025 to August 2026, and only July 2026 came in lower. Split the month at 20 December, where the holiday window starts, and the two halves ran within about a point of each other. The first nineteen days, before any holiday traffic, were barely better than the fortnight everyone fears.
What makes December bad is where the airports are.
The holiday rush lands on top of that.
North and south
US average 73.2%
55.0%90.0%
Flights departing each airport in December 2025, scored on arrival. The dashed line is the national December figure. Source: US DOT Bureau of Transportation Statistics, September 2025 to August 2026.
Chicago (ORD) came last at 61.0%, just behind Detroit in December at 62.0% and LaGuardia at 62.2%. Minneapolis in December ran 63.1% against 79.2% for its year, the largest fall of any airport in the data. December was the worst month of the twelve for Minneapolis, Detroit, O'Hare, LaGuardia, JFK, Newark, Boston, Philadelphia and most of the Ohio Valley.
At the top, Salt Lake City (SLC) held 83.8%, and behind it came a run of southern and south-western airports: San Antonio, Albuquerque, Ontario, Houston Hobby. Several of them ran December better than their own annual average. Hobby's December, at 82.0%, beat its year by some distance, and Dallas Love Field in December ran 78.7% against 72.6% annually. For Texas and the desert, December is a good month.
Minneapolis (MSP)79.2% overall
Chicago (ORD)70.8% overall
Detroit (DTW)76.7% overall
Houston (HOU)76.5% overall
Dallas (DAL)72.6% overall
Las Vegas (LAS)76.9% overall
All panels share one scale. December is the last column. Source: US DOT Bureau of Transportation Statistics, September 2025 to August 2026.
The small multiples make the split visible. The northern panels drop in December and again in January; the southern ones stay level or rise, and their bad month is in summer.
The winter mechanism
Snow and ice slow an airport in several ways at once. Runway acceptance rates fall when braking action is poor and when snow has to be cleared between arrival streams. Every departure needs de-icing, which adds a queue at the pads and a hold-over time the crew cannot exceed. Low cloud and poor visibility widen the spacing between arrivals. A hub in that condition processes fewer flights per hour than its schedule assumes, and the gap is paid in delay by every bank that follows.
The cause codes show only part of this. At O'Hare, extreme weather accounted for 10% of delay minutes across the full year and a noticeably larger share in December. Most winter weather delay, though, is coded as air traffic system delay (the arrival rate cut) or as late-arriving aircraft (the plane that sat at a de-ice pad in Minneapolis and arrived late somewhere else). Across the year, 40% of all delay minutes fell in the late-aircraft category.
The holidays add the second layer. From the third week of December aircraft are full, spare seats disappear, and a flight cancelled for weather often cannot be rebooked for a day or more. The Christmas and New Year guide covers those two weeks; the 2025 holiday window ran 72.4% on time against 78.9% in the normal weeks around it, 6.5 points worse.
Airlines: the hub map decides
US average 73.2%
55.0%80.0%
Source: US DOT Bureau of Transportation Statistics, September 2025 to August 2026.
I read the December airline ranking as a hub map more than a league table. United Airlines led December at 77.2%. That is a change from most of the year, when Delta leads the big carriers. Delta ran 74.5% in December against 81.1% for its year, while United ran 77.2% against 78.8%.
The difference is geography. Delta's second and third hubs are Minneapolis and Detroit, and both were among the worst airports in the country in December. Delta at Minneapolis and Delta at Detroit both ran far below their annual level. United's Houston hub had a good December: United at Houston Intercontinental ran above its annual level there. Southwest, with the largest Sun Belt network, ran 75.4%, close to its annual 75.7%, and Southwest at Hobby ran well above its annual level at the airport.
US average 73.2%
40.0%90.0%
Bars are December 2025; the figure under each is the full-year rate at that airport. Source: US DOT Bureau of Transportation Statistics, September 2025 to August 2026.
The regional carriers took the worst of it at the northern hubs. SkyWest at O'Hare ran the weakest December of any large airline-at-airport operation, and SkyWest at Detroit was not far behind. Regional jets fly the short spokes into those hubs from smaller airports in the same snow belt, so they likely absorb the storms at both ends of the trip, and short regional legs are the first an airline cancels when a hub's arrival rate is cut.
JetBlue Airways finished last at 63.9%, with JetBlue at Boston and at JFK both running December far below their annual level.
Hawaii and Florida are not immune
Sun does not guarantee a good December. Honolulu in December ran 76.1% against 82.1% for its year, and Hawaiian Airlines had its worst month of the year in December. Fort Lauderdale ran 64.9%.
That Hawaiian figure needs a footnote. Hawaiian is reported under its own code only from August to December 2025; from January 2026 the same flights, inter-island included, appear under Alaska's code. I noticed it when the Honolulu to Kahului route split into two carrier files. So "its worst month of the year" means its worst of five months, all of them in the second half of 2025.
The data does not show a single cause for Honolulu: most of its December delay minutes were coded to the airlines themselves or to late-arriving aircraft, with very little charged to weather. Fort Lauderdale's is easier to read. December is the start of the Florida high season, and much of the airport's flying likely turns aircraft that arrive from the north, where December was at its worst.
If it were my December ticket
Connect south or west. In December 2025 a connection through Houston, Dallas Love Field, Phoenix or Salt Lake City was far safer than one through Minneapolis, Detroit or Chicago. If your airline offers both, the southern routing is the December choice even when it adds distance. At 63.1% on time in December 2025, Minneapolis is the hub I would route around.
Take the first wave, and have a plan for the whole day. A winter storm does not respect departure windows the way a summer thunderstorm does; it can shut an airport all day. Added up across the December pages of all 60 airports, even the 5am–8am departures ran about five points below the 89.3% that window manages over the full year, because overnight snow and de-icing reach the first departures too. The first flight still has the most options behind it if it cancels.
Do not assume early December is safe. The first three weeks of December 2025 were almost as weak as the holiday fortnight. The difference is that before the 20th cancellations were rarer and flights less full, so a cancelled passenger was likely to find a seat sooner.
Check the airport's December page, not its annual one. For the northern hubs the gap between the two is large enough to change the decision. The winter storm guide covers January and February, which share the same mechanism.
Check the December pages: Minneapolis in December · O'Hare in December · Houston Hobby in December · Salt Lake City in December · Compare any US route