Route reliability record
BWI→IAH
Baltimore to Houston
- Flights
- 1,307
- Period
- September 2025 to August 2026
- Distance
- 1,235 mi
- Carriers
- 4
This route lands a B, about a point better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by an hour and a half on average. That rests on 1,307 BWI to IAH flights, with a median arrival 11 minutes early.
Best time to fly BWI to IAH: a 5am–8am departure, ideally on a Thursday. Flights in that window arrived on time 92.1% of the time and Thursday flights 85.0%, against 78.3% for the route overall.
The US average over the same twelve months is 77.3%, 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
78.3%
Arrivals under 15 minutes late, of 1,278 completed flights
Avg delay
83 min
Across delayed arrivals only, not all flights
Cancelled
2.07%
National rate is 1.89%
Best carrier
United
84.0% on time across 833 flights
These figures cover 1,307 flights between September 2025 and August 2026. Beyond the headline rate, 8.3% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Which airline is most reliable on BWI 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 | 1 | 100.0% | — | 0.00% | A+ |
| United Airlines | 833 | 84.0% | 68 min | 1.20% | B |
| Spirit Airlinesthin sample | 293 | 73.3% | 103 min | 2.73% | C |
| Frontier Airlinesthin sample | 180 | 59.1% | 90 min | 5.00% | D− |
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Best ways to make this trip
The most reliable ways to fly Baltimore to Houston
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 4 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. IAD → IAHWashington to Houston | United Airlines | 84.3% | 84.7% | 0.48% | 5am–8am, Tue | UA 1524 08:30 |
| 2. BWI → IAHBaltimore to Houston | United Airlines | 83.0% | 84.0% | 1.20% | 5am–8am, Thu | — |
| 3. DCA → IAHWashington to Houston | United Airlines | 82.8% | 83.5% | 0.80% | 5am–8am, Wed | UA 1450 06:00 |
| 4. BWI → HOUBaltimore to Houston | Southwest Airlines | 74.6% | 75.7% | 1.43% | 5am–8am, Wed | — |
| 5. DCA → HOUWashington to Houston | Southwest Airlines | 73.8% | 75.4% | 2.18% | 5am–8am, Wed | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
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 28 points, against half a point between the best and worst carrier.
- 5am–8am281 flights92.1%
- 8am–11am102 flights92.0%
- 11am–2pm287 flights83.1%
- 2pm–5pm295 flights70.6%
- 5pm–8pm230 flights63.7%
- 8pm–5am112 flights68.3%
Scale runs 55% to 100%.
The 5pm–8pm window is where this operation falls apart: 63.7% on time, against 92.1% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 2pm–5pm window is the busiest, with 295 flights scheduled in it.
Explore
Filter BWI to IAH by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On BWI to IAH, the best departure window is 5am–8am at 92.1% on time and the worst is 5pm–8pm at 63.7%, a wide gap of 28.4 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am92.1%
- 8–11am92.0%
- 11am–2pm83.1%
- 2–5pm70.6%
- 5–8pm63.7%
- 8pm–5am68.3%
best all US flightsScale 55% to 95%.
Across the year
When delays peak on this route
This route's year swings by 22 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.
September is the best month on the calendar at 88.7% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. November was the busiest month here, with 123 flights.
Across the week, Thursday is the strongest day at 85.0% on time and Friday the weakest at 74.1%, a spread of 11 points.
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 23,000 reported delay minutes.
- 37%National Airspace System
- 32%Late-arriving aircraft
- 26%Carrier
- 5%Extreme weather
- 0%Security
37% 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 8,401 minutes out of 23,000, against a national NAS share of 21%. The split is drawn from 22,998 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 92.1% on time here.
Cancellations sit at 2.07% against a national 1.89%, which is ordinary. Diversions add another 0.15%.
Connections and stage length
What a delay here actually costs
8.3% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last an hour and a half, which a normal layover absorbs.
The 1,235 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.
The return leg runs 77.3% on time across 1,308 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 1,307 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.
Work out the risk of missing a connection in IAH after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 88.7% on time and May 67.0%, a swing of 22 points. If the dates move at all, move them out of May before you think about anything else. 1,278 completed flights over 12 months sit behind that.
Common questions
BWI to IAH questions
How often is BWI to IAH delayed?
About one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 21.7% of the 1,307 flights in this analysis, against 22.7% nationally. Delayed flights are late by an hour and a half on average.
How reliable is BWI to IAH compared with the rest of the country?
78.3% of flights arrive on time here against a national 77.3%, a difference of about a point in its favour. That is worth a B on this site's grading scale.
What time of day has the fewest delays on BWI to IAH?
The 5am–8am departure window is the strongest at 92.1% on time. The 5pm–8pm window is the weakest at 63.7%, 28 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 May delays on BWI to IAH?
May is the weakest month at 67.0% on time, compared with 88.7% in September. Across the year that is 22 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 BWI — the return legseparate record
- Baltimore/Washington International Thurgood Marshall (BWI) delay statistics
- George Bush Intercontinental (IAH) delay statistics
- United Airlines on BWI to IAH84.0%
- Spirit Airlines on BWI to IAH73.3%
- Frontier Airlines on BWI to IAH59.1%
- BWI to ATL, a related route79.9%
- ORD to IAH, a related route76.0%
- BWI to MCO, a related route75.5%
- SkyWest Airlines on-time record100.0%
- United Airlines on-time record84.0%
- Spirit Airlines on-time record73.3%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Direction matters. BWI to IAH and IAH to BWI are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.