Guide
Flying in August: an average month hiding two different summers
August 2025 ran 73.1% on time, level with the year's 77.3%. Boston had its best month of the twelve; Dallas-Fort Worth ran 73.5%. Why August splits the map.
August 2025 ran 73.1% on time. The full year from September 2025 to August 2026 ran 77.3%. On the national figure alone, August is the most ordinary month in the data, neither the summer collapse of July nor the calm of September.
The national figure is an average of two summers happening at once. In the Northeast and around the Great Lakes, August was one of the best months of the year. At Dallas-Fort Worth, Houston Intercontinental, the big Florida airports and Denver it was one of the worst. Where you fly from decides which August you get.
One caution first. Each month in this data is a single month of a single year, and August here is August 2025 while July is July 2026. The two are not consecutive, so the July-to-August comparison some readers will want to make is really a comparison between two different summers. (August 2026 is not here yet: the DOT publishes each month about two months late, and the pipeline picks it up when the file appears.)
The ranking
US average 73.1%
55.0%90.0%
Flights departing each airport in August 2025, scored on arrival. The dashed line is the national August figure. Source: US DOT Bureau of Transportation Statistics, September 2025 to August 2026.
Kahului (OGG) led at 85.6%, with Honolulu in August close behind at 80.2%. Chicago (ORD) came last at 64.6%. The median airport ran 74.4%, and 7 of the 59 airports reached 80%, several times as many as in July.
The top of the table mixes the usual western names, Burbank at 78.1% and Salt Lake City at 78.3%, with some that rarely appear there. That second group is where August gets interesting.
The Northeast's good month
US average 73.1%
55.0%85.0%
Bars are August 2025 on-time rates; the figure under each airport is its full-year rate. Source: US DOT Bureau of Transportation Statistics, September 2025 to August 2026.
Boston in August ran 69.8% on time against 74.6% for its year, and Boston's best month of all twelve was May. LaGuardia ran 68.2%, some way above its annual 72.4%. Detroit (78.4%) and Nashville (70.1%) followed the same pattern.
These are airports whose normal problem is volume. LaGuardia and Boston run close to their runway capacity through most of the year, and their cancellation rates, 5.04% and 3.05% annually, are among the highest in the country. August is the month business travel thins out, and in August 2025 the corridor also escaped the lines of storms that wrecked its July 2026. With fewer flights competing for the same runways and little weather, the airports ran close to what they can do on a good day. LaGuardia's regional flying showed it most: Republic at LaGuardia, which flies regional jets from the field for the big network carriers, ran its August well above its annual record.
The chart also shows the other half of the country. The lower bars belong to hubs that are either in the storm belt or at altitude.
The storm-belt hubs and Denver: the bad half
Dallas-Fort Worth in August ran 73.5%, against 72.8% for the year. Orlando managed 68.3%, and Orlando's worst month of the twelve was July. Miami ran 73.4%.
The mechanism is the one the summer thunderstorm guide describes: sea-breeze storms over the Florida peninsula most afternoons, and convection over North Texas that shuts arrival streams into the biggest hub in the South. At Orlando the extreme-weather column carried more than twice its usual share of August delay minutes (across the full year it is 5%), and most weather delay does not even land in that column. It sits in the air traffic and late-aircraft categories, because a storm that holds an arrival bank shows up as late aircraft on every flight that follows.
The carrier breakdown at those airports points one way.
US average 73.1%
50.0%90.0%
Bars are August 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.
American at Dallas-Fort Worth ran the weakest August of any airline-at-airport operation on this site, and American at Miami and Orlando were not far behind. American's network is anchored in Dallas-Fort Worth, Charlotte and Miami, all three in the summer storm belt, and all three ran their August below American's own annual level there. That goes a long way to explaining why American finished last among airlines in August.
Denver is the other outlier. Denver in August ran 67.1%, among the worst of the month, against a Denver November that was the airport's best month of the year. Afternoon storms over the Front Range close runways and halt ramp work for lightning, and both big carriers paid for it: Southwest at Denver and United at Denver each ran their August well below their own annual level at the airport.
Seattle does not fit either story. Seattle in August ran 72.6%, well under its annual 79.5%, with almost none of its delay coded to weather. The shortfall sat largely with Alaska at Seattle, whose August was far below its own annual level while SkyWest's flights from the same airport ran normally. One month cannot say why; it points at the operation rather than the sky. I would want to see a second August before calling it a pattern.
Airlines in August
US average 73.1%
55.0%85.0%
Source: US DOT Bureau of Transportation Statistics, September 2025 to August 2026.
Envoy Air led at 79.8%, followed by Republic and Delta at 75.8% and 78.4%. JetBlue Airways finished last at 64.0%, with Frontier (66.6%) and Alaska (75.5%) next. Alaska's August was one of its two weakest months of the year, which is unusual for the carrier ranked near the top on most annual measures.
Labor Day at the end of the month
The Labor Day weekend in 2025 began on Friday 29 August and ran 81.0% on time against 81.5% in the normal weeks around it, 0.5 points worse. Nationally the holiday barely registered. Dallas-Fort Worth was the exception, with a weekend far worse than the rest of the country. The Labor Day guide breaks the weekend down airport by airport.
What I would book in August
Route through the northern hubs. In August 2025 a connection through Detroit (78.4%) or Salt Lake City (78.3%) beat one through Dallas-Fort Worth (73.5%) or Denver (67.1%) by double digits. That gap is the single largest lever available in August.
At 73.5% on time, I would not put a tight August connection through Dallas-Fort Worth.
At the storm-belt hubs, fly before noon. The storms that make August bad at Orlando, Miami and Dallas-Fort Worth build through the afternoon. A morning departure leaves before they form; an evening one inherits every delay they cause. Added up across the August pages of all 59 airports, the 5pm–8pm departures ran about twenty-five points behind the 5am–8am ones, a wider gap than the 21.3 points for the full year.
Treat the Northeast as the good news it was, cautiously. One calm August does not make the corridor reliable. Boston and LaGuardia still cancel more than almost anywhere over a full year, and a single storm line can reverse the picture.
Allow longer connections on American's southern hubs. When the storm belt and a single carrier's biggest hubs overlap, a missed connection has fewer alternatives. The connection risk tool shows how often a given layover fails.
Check the August pages: Dallas-Fort Worth in August · Orlando in August · Boston in August · Detroit in August · Compare any US route