Route reliability record
BWI→IAH
Baltimore to Houston
- Flights
- 1,311
- Period
- July 2025 to June 2026
- Distance
- 1,235 mi
- Carriers
- 4
This route lands a B, 2 points better than the national rate of 77.6%. 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 is a workable record, not a spotless one. That rests on 1,311 BWI to IAH flights, of which United Airlines flew 816 at 83.2% on time.
Best time to fly BWI to IAH: a 8am–11am departure, ideally on a Thursday. Flights in that window arrived on time 91.9% of the time and Thursday flights 85.8%, against 79.8% for the route overall.
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
79.8%
Arrivals under 15 minutes late, of 1,284 completed flights
Avg delay
89 min
Across delayed arrivals only, not all flights
Cancelled
1.83%
National rate is 1.81%
Best carrier
United
83.2% on time across 816 flights
These figures cover 1,311 flights between July 2025 and June 2026. The median arrival is 12 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 BWI to IAH
The choice of carrier is not cosmetic here. United Airlines arrives on time 83.2% of the time; Spirit Airlines manages 76.5%. Sample sizes sit next to every figure, because a two-point gap across 376 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlinesthin sample | 1 | 100.0% | — | 0.00% | A+ |
| United Airlines | 816 | 83.2% | 80 min | 1.10% | B |
| Spirit Airlines | 376 | 76.5% | 108 min | 2.66% | B |
| Frontier Airlinesthin sample | 118 | 66.4% | 77 min | 4.24% | C− |
United leads Spirit by 7 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
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 | 83.3% | 83.7% | 0.48% | 5am–8am, Tue | UA 1524 08:30 |
| 2. DCA → IAHWashington to Houston | United Airlines | 83.0% | 83.8% | 0.91% | 5am–8am, Tue | UA 1450 06:00 |
| 3. BWI → IAHBaltimore to Houston | United Airlines | 82.3% | 83.2% | 1.10% | 5am–8am, Tue | — |
| 4. DCA → HOUWashington to Houston | Southwest Airlines | 76.1% | 77.5% | 1.80% | 5am–8am, Mon | — |
| 5. BWI → HOUBaltimore to Houston | Southwest Airlines | 75.1% | 76.3% | 1.58% | 5am–8am, Tue | — |
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 27 points, against 7 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am328 flights91.7%
- 8am–11am113 flights91.9%
- 11am–2pm256 flights84.3%
- 2pm–5pm275 flights73.3%
- 5pm–8pm227 flights64.6%
- 8pm–5am112 flights68.3%
Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 64.6% on time, against 91.9% for the 8am–11am 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 5am–8am window is the busiest, with 328 flights scheduled in it.
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 85.8% on time and Friday the weakest at 75.5%. 10 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 23,000 reported delay minutes.
- 33%Carrier
- 33%National Airspace System
- 27%Late-arriving aircraft
- 7%Extreme weather
- 0%Security
33% 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 7,473 minutes out of 23,000, against a national NAS share of 21%. The split is drawn from 22,972 reported delay minutes.
Cancellations sit at 1.83% against a national 1.81%, which is ordinary. Diversions add another 0.23%.
Connections and stage length
What a delay here actually costs
7.9% 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 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. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The return leg is a different operation and performs like one: it runs 75.8% on time across 1,311 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 1,311 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. 1,284 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 20.2% of the 1,311 flights in this analysis, against 22.4% nationally. Delayed flights are late by an hour and a half on average.
Which airline is most reliable on BWI to IAH?
United Airlines leads at 83.2% on time across 816 flights. Spirit Airlines is at the other end on 76.5%, a gap of 7 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on BWI to IAH?
The 8am–11am departure window is the strongest at 91.9% on time. The 5pm–8pm window is the weakest at 64.6%, 27 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 IAH83.2%
- Spirit Airlines on BWI to IAH76.5%
- Frontier Airlines on BWI to IAH66.4%
- BWI to ATL, a related route80.6%
- ORD to IAH, a related route75.0%
- BWI to MCO, a related route75.6%
- SkyWest Airlines on-time record100.0%
- United Airlines on-time record83.2%
- Spirit Airlines on-time record76.5%
- 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. 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.
Embed BWI to IAH’s on-time badge on your site
Paste this into a web page. The badge shows the current on-time rate, cancellation rate and grade, and updates every month. Preview it, or build a badge for another route or airport.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.