Route reliability record
IAH→AUS
Houston to Austin
- Flights
- 2,675
- Period
- July 2025 to June 2026
- Distance
- 140 mi
- Carriers
- 2
This route lands a B+, 2 points better than the national rate of 77.6%. About one flight in five arrive 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 2,675 flights, with a median arrival 5 minutes early.
The US average over the same twelve months is 77.6%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
79.4%
Arrivals under 15 minutes late, of 2,652 completed flights
Avg delay
66 min
Across delayed arrivals only, not all flights
Cancelled
0.79%
National rate is 1.81%
Best carrier
United
79.4% on time across 2,609 flights
These figures cover 2,675 flights between July 2025 and June 2026. The median arrival is 5 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
Carrier by carrier
Which airline is most reliable on IAH to AUS
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlinesthin sample | 66 | 81.8% | 104 min | 0.00% | B+ |
| United Airlines | 2,609 | 79.4% | 65 min | 0.80% | B+ |
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 17 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am313 flights90.7%
- 8am–11am337 flights86.3%
- 11am–2pm344 flights82.4%
- 2pm–5pm639 flights73.3%
- 5pm–8pm371 flights76.1%
- 8pm–5am671 flights76.9%
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 90.7% of the time, against 73.3% for the afternoon 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 8pm–5am window is the busiest, with 671 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 25 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
July is the worst month at 65.2% on time, 25 points below February, the best at 90.1%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. January was the busiest month here, with 239 flights.
Across the week, Tuesday is the strongest day at 85.1% on time and Sunday the weakest at 72.2%. 13 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
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 36,000 reported delay minutes.
- 36%Late-arriving aircraft
- 32%Carrier
- 25%National Airspace System
- 7%Extreme weather
36% 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 36,000 reported delay minutes here, that single category outweighs weather by 5 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 35,976 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 90.7% on time here.
Cancellations are rare at 0.79%, below the national 1.81% 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.
Connections and stage length
What a delay here actually costs
7.2% of arrivals land an hour or more late, close to the national 8.1%. 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 are the about an hour kind, which a normal layover absorbs.
At 140 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 5am–8am window matters as much as it does.
The return leg is a different operation and performs like one: it runs 75.6% on time across 2,674 flights, 4 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 4 points of difference.
The sample behind these figures is 2,675 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 90.1% on time and July 65.2%, a swing of 25 points. If the dates move at all, move them out of July before you think about anything else. 2,652 completed flights over 12 months sit behind that.
Common questions
IAH to AUS questions
How often is IAH to AUS delayed?
About one flight in five arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 20.6% of the 2,675 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
How reliable is IAH to AUS compared with the rest of the country?
79.4% of flights arrive on time here against a national 77.6%, a difference of 2 points in its favour. That is worth a B+ on this site's grading scale.
What time of day has the fewest delays on IAH to AUS?
The 5am–8am departure window is the strongest at 90.7% on time. The 2pm–5pm window is the weakest at 73.3%, 17 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are July delays on IAH to AUS?
July is the weakest month at 65.2% on time, compared with 90.1% in February. Across the year that is 25 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- AUS to IAH — the return legseparate record
- George Bush Intercontinental (IAH) delay statistics
- Austin-Bergstrom International (AUS) delay statistics
- SkyWest Airlines on-time record81.8%
- United Airlines on-time record79.4%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. IAH to AUS and AUS to IAH are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.