Each and every summer, social media and news headlines seemingly get filled with massive flight delays and cancellations. There’s an easy solution to drastically improve the odds that you’ll get where you need to go on time:
Book the earliest flight you can.
According to an analysis Thrifty Traveler conducted using U.S. Department of Transportation on-time performance data from May 2024 to April 2025 via Cirium Diio, we found that despite winter storms, the summer months see far more delays and cancellations than the rest of the year … and that in the worst-performing months, the earliest morning flights are 30% more likely to depart on time compared to afternoon or evening flights.
Our analysis went even deeper, though, showing that:
- Morning departures are even more important flying in and out of the South and East Coast, where airports have the worst operations and largest drop-offs in evening flight performance.
- Meanwhile, airports in Western and Southwestern states perform the best.
- That trend also manifests itself in American Airlines seeing the brunt of the worst operations – and Alaska Airlines operating best.
- Flights departing between 6 a.m. and 11 a.m. are the five best hours of the day for U.S. flights.
- But there’s a steep drop-off between 4 p.m. and 5 p.m., culminating in the worst five-hour stretch for on-time flights: 7 p.m. to midnight.
For years, we’ve been urging travelers to book the first flight of the day if you absolutely have to be somewhere – or if you’re just desperate to avoid disruptions. This analysis shows it’s even more important than we suspected.
Read next: How to Avoid Delays and Cancellations
Summer’s the Worst: Flight Delays and Cancellations
You’re not imagining things: summertime airline operations lag considerably behind the other months of the year. There are a few reasons for that.
For one, summer is just a busier travel season than fall, winter, and spring – it’s when families, teachers, and academics are also taking to the skies along with everyone else, filling up planes, tarmacs, and terminals. More delays and cancellations should be expected with that kind of swell.
But as the hour-by-hour data shows (more on that later), weather also plays a part, with summertime storms hurting operations – especially in the evenings – at some of the nation’s busiest airports. While the occasional winter storm can lead to a one-off meltdown, ugly summer weather is a constant problem.
So if you’re traveling in the summer, be prepared for the worst. Across the U.S. in July 2024, for example, fewer than 70% of domestic flights operated on-time, according to the data – and that number was 75% or below for June and August as well. But the on-time performance improves as travel quiets down throughout the country in the fall, dipping slightly into the winter months when blizzards and ice tend to wreak havoc once again.
Still, summertime travel is far more likely to be disrupted than winter travel, according to DOT data from the past year.
When During the Day are Flight Delays and Cancellations Worst?
In July 2024 – the worst month for delays and cancellations in the U.S. over the past year of available DOT data – the first flights of the day were 30% more likely to operate on time than the last ones.
So let me say it again: Book the first flight of the day!
No matter the time of year, airlines typically start off the day strong. In both January and July of last year, more than 80% of domestic flights before 8 a.m. departed on time.
But by 10 p.m. and onward, that dropped to 53% of the time – a 30% drop, with an average delay of 33 minutes. In January, on-time percentages only fell by 8% by the end of the day.
Break it down hour-by-hour, and the data gets even clearer. According to our analysis, the five best times for departing flights were:
- 7 a.m. – 84.3% on time
- 8 a.m. – 84.3%
- 9 a.m. – 83.2%
- 6 a.m. – 82.1%
- 10 a.m. – 82.0%
It’s no coincidence that those all start off the day. Maybe you can venture a guess what the worst-performing hours were…
- 11 p.m. – 56.7% on time
- 9 p.m. – 58.5%
- 10 p.m. – 58.6%
- 7 p.m. – 59.6%
- 8 p.m. – 61.6%
So we know that the earlier you fly, the better off you’ll be – and that the last few flights of the day are the most perilous, but when do things turn for the worst?
We analyzed the steepest hour-to-hour drop-offs in average on-time performance from July and found that things really start to get bad between 4 p.m. and 5 p.m., with a 6.18% drop-off in on-time performance.
Which Airlines are Worst for Summer Delays & Cancellations?
Some airlines perform better than others. That’s a simple fact of flying in the U.S. But it’s especially stark when you look at how airlines fare as the day drags on, because some carriers drop off significantly while others hold steady throughout the day.
For this analysis, we again looked at July 2024 – the worst-performing month – to see which airline’s on-time performance suffered the most as the day went on. Remember: This is last summer’s data – not this year.
Here’s a chart plotting the nation’s major airlines: American, Alaska, Delta, JetBlue, United, and Southwest.
Note: This data only includes mainline flights on the major carriers – not subsidiaries and regional carriers like SkyWest, which operates on behalf of several major carriers.
As you can see, American Airlines struggled mightily in the afternoons and evenings – likely because of its high exposure to Southern and Eastern hubs like Charlotte (CLT), Miami (MIA), and Dallas-Fort Worth (DFW) – more on that later. Alaska, on the other hand, with its predominantly Western network, saw considerably less fall-off in performance throughout the day.
What’s the common thread here? Where these airlines operate
Which Airports & Regions Suffer the Most
South & East Coast Airports Struggle
The 10 worst airports in the U.S. for on-time operations (that operated at least 1,000 flights in July 2024) were all in the Southern and Eastern U.S.
- Houston-Intercontinental (IAH) – 55% on-time departure
- Charlotte (CLT) – 55%
- Baltimore (BWI) – 58%
- Atlanta (ATL) – 59%
- Asheville (AVL) – 61%
- Dallas-Fort Worth (DFW) – 62%
- Newark (EWR) – 62%
- Miami (MIA) – 63%
- Orlando (MCO) – 63%
- Houston-Hobby (HOU) – 63%
- New Orleans (MSY) – 63%
We actually listed 11 here because there was a four-way tie for eighth.
It’s an undeniable trend … that’s even more stark when you put them on a map.
Some airports’ problems are particularly bad as the day goes on.
For example, 82% of flights from Charlotte (CLT) departed on time at the start of the day last July. But by the end of the day, that fell to just 37% between 6 p.m. and 10 p.m – a 45% drop in on-time performance. Orlando (MCO) was not far behind with a 44% drop throughout the course of the day, followed by Asheville (AVL) with a 41% decline.
The Best (Airports) are Out West
It’s not all bad news! On the other side of the country, things were much, much better.
With (mostly) sunny skies year-round, it should be no surprise that the Hawaiian airports of Kona (KOA), Maui (OGG), Kauai (LIH), and Honolulu (HNL) were the four best-performing airports across the country, with overall on-time performance last July between 83% and 87%. But many U.S. airports on the mainland were close behind Hawaii, with the top 13 also having a distinct regional bent.
- Boise (BOI) – 81% of on-time departures
- Long Beach (LGB) – 81%
- Spokane (GEG) – 81%
- San Jose (SJC) – 80%
- Ontario (ONT) – 80%
- Portland (PDX) – 79%
- Burbank (BUR) – 79%
- Oakland (OAK) – 78%
- Colorado Springs (COS) – 77%
- Santa Ana (SNA) – 77%
- Tucson (TUS) – 77%
- Wichita (ICT) – 77%
- Sacramento (SMF) – 77%
We listed the 13 best because there was a five-way tie for ninth.
As you can tell, the best performing airports in July 2024 all come from the Western U.S.
Bottom Line
On-time performance data for the United States makes one thing abundantly clear: The earlier you book your flight, the more likely it is to be on-time … especially in the summer.
Flight delays and cancellations cascade throughout the day, leading to a 30% reduction in on-time flights by the end of the day, according to our analysis of July 2024 on-time data. The summer months are by far the worst for delays and cancellations, and the airports and airlines in the Southern and Eastern part of the United States bear the brunt of delays and cancellations.
That 4 a.m. wake-up call might be brutal … but if getting to your destination on-time is your top priority, it’s the best decision you can make.
