Route reliability record
SAT→IAH
San Antonio to Houston
- Flights
- 2,410
- Period
- July 2025 to June 2026
- Distance
- 191 mi
- Carriers
- 2
This route lands a B+, 4 points better than the national rate of 77.6%. Roughly 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 2,410 flights, with a median arrival 6 minutes early.
Set against the rest of the country, this route's record is 4 points better than the US average of 77.6%. That gap is worth roughly 40 fewer late arrivals for every thousand flights.
Key figures
On time
81.6%
Arrivals under 15 minutes late, of 2,391 completed flights
Avg delay
64 min
Across delayed arrivals only, not all flights
Cancelled
0.71%
National rate is 1.81%
Best carrier
United
81.5% on time across 2,324 flights
These figures cover 2,410 flights between July 2025 and June 2026. The median arrival is 6 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 SAT to IAH
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 | 86 | 82.4% | 91 min | 1.16% | B |
| United Airlines | 2,324 | 81.5% | 63 min | 0.69% | 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 10 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–8am619 flights84.3%
- 8am–11am350 flights83.8%
- 11am–2pm253 flights88.1%
- 2pm–5pm636 flights78.0%
- 5pm–8pm552 flights78.1%
- 8pm–5am—
Scale runs 70% to 95%. Rows with fewer than 30 flights show a dash.
The best window here is not the first bank but the 11am–2pm slot at 88.1% on time, ahead of 2pm–5pm at 78.0%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 2pm–5pm window is the busiest, with 636 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 19 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.
Delays peak in October, when the on-time rate falls to 72.2%. January is the strongest month at 91.6%. Moving a flexible trip across that boundary buys 19 points. March was the busiest month here, with 233 flights.
Across the week, Tuesday is the strongest day at 87.9% on time and Friday the weakest at 77.8%. 10 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. National Airspace System accounts for 46% of the 28,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 46%National Airspace System
- 28%Late-arriving aircraft
- 24%Carrier
- 2%Extreme weather
46% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 13,000 minutes out of 28,000, against a national NAS share of 21%. The split is drawn from 28,008 reported delay minutes.
Cancellations are rare at 0.71%, 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
5.3% 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 191 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 11am–2pm window matters as much as it does.
The return leg runs 82.4% on time across 2,411 flights, within about a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 2,410 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. January runs 91.6% on time and October 72.2%, a swing of 19 points. If the dates move at all, move them out of October before you think about anything else. 2,391 completed flights over 12 months sit behind that.
Common questions
SAT to IAH questions
How often is SAT to IAH delayed?
Roughly 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 18.4% of the 2,410 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
How reliable is SAT to IAH compared with the rest of the country?
81.6% of flights arrive on time here against a national 77.6%, a difference of 4 points in its favour. That is worth a B+ on this site's grading scale.
What time of day has the fewest delays on SAT to IAH?
The 11am–2pm departure window is the strongest at 88.1% on time. The 2pm–5pm window is the weakest at 78.0%, 10 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 October delays on SAT to IAH?
October is the weakest month at 72.2% on time, compared with 91.6% in January. Across the year that is 19 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
- IAH to SAT — the return legseparate record
- San Antonio International (SAT) delay statistics
- George Bush Intercontinental (IAH) delay statistics
- SkyWest Airlines on-time record82.4%
- United Airlines on-time record81.5%
- The best time of day to fly, according to 7.04 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. SAT to IAH and IAH to SAT 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.