Route reliability record
IAH→BWI
Houston to Baltimore
- Flights
- 1,308
- Period
- September 2025 to August 2026
- Distance
- 1,235 mi
- Carriers
- 4
This route lands a B, level with the national rate of 77.3%. Roughly one flight in four arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 1,308 IAH to BWI flights, with a median arrival 4 minutes early.
Best time to fly IAH to BWI: a 11am–2pm departure, ideally on a Wednesday. Flights in that window arrived on time 86.4% of the time and Wednesday flights 82.0%, against 77.3% 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
77.3%
Arrivals under 15 minutes late, of 1,281 completed flights
Avg delay
64 min
Across delayed arrivals only, not all flights
Cancelled
1.91%
National rate is 1.89%
Best carrier
United
81.3% on time across 831 flights
These figures cover 1,308 flights between September 2025 and August 2026. The median arrival is 4 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.
Fare search by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Carrier by carrier
Which airline is most reliable on IAH to BWI
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 | 2 | 100.0% | — | 0.00% | A+ |
| United Airlines | 831 | 81.3% | 60 min | 0.60% | B+ |
| Spirit Airlinesthin sample | 295 | 79.9% | 59 min | 2.03% | B |
| Frontier Airlinesthin sample | 180 | 52.1% | 73 min | 7.78% | F− |
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Best ways to make this trip
The most reliable ways to fly Houston to Baltimore
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. IAH → IADHouston to Washington | United Airlines | 82.0% | 82.4% | 0.43% | 5am–8am, Mon | UA 1549 07:20 |
| 2. IAH → BWIHouston to Baltimore | United Airlines | 80.8% | 81.3% | 0.60% | 5am–8am, Tue | — |
| 3. IAH → DCAHouston to Washington | United Airlines | 76.2% | 76.7% | 0.67% | 5am–8am, Tue | UA 654 12:00 |
| 4. HOU → BWIHouston to Baltimore | Southwest Airlines | 73.9% | 74.9% | 1.35% | 5am–8am, Wed | — |
| 5. IAH → DCAHouston to Washington | Republic Airways | 72.2% | 75.9% | 4.87% | 5am–8am, Sat | — |
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 34 points, against half a point between the best and worst carrier.
- 5am–8am416 flights84.6%
- 8am–11am14 flights—
- 11am–2pm376 flights86.4%
- 2pm–5pm149 flights52.2%
- 5pm–8pm327 flights68.8%
- 8pm–5am26 flights—
Scale runs 45% to 90%. Rows with fewer than 30 flights show a dash.
The best window here is not the first bank but the 11am–2pm slot at 86.4% on time, ahead of 2pm–5pm at 52.2%. 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 5am–8am window is the busiest, with 416 flights scheduled in it.
Explore
Filter IAH to BWI 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 IAH to BWI, the best departure window is 11am–2pm at 86.4% on time and the worst is 2pm–5pm at 52.2%, a wide gap of 34.2 points. All US flights leaving 11am–2pm ran 78.3%.
- 5–8am84.6%
- 8–11am—
- 11am–2pm86.4%
- 2–5pm52.2%
- 5–8pm68.8%
- 8pm–5am—
best all US flightsScale 45% to 95%. Cells under 30 flights show a dash.
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 63.5% on time, 25 points below January, the best at 88.4%. 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. November was the busiest month here, with 122 flights.
Across the week, Wednesday is the strongest day at 82.0% on time and Sunday the weakest at 70.9%, a spread of 11 points.
Delay causes
Why this route gets delayed
Carrier accounts for 44% of the 18,000 delay minutes carriers reported here, and the remaining four split what is left.
- 44%Carrier
- 30%Late-arriving aircraft
- 21%National Airspace System
- 4%Extreme weather
- 0%Security
The largest share of delay minutes, 44%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 8,175 of the 18,000 delay minutes reported here. The split is drawn from 18,483 reported delay minutes.
Cancellations sit at 1.91% against a national 1.89%, which is ordinary. Diversions add another 0.15%.
Connections and stage length
What a delay here actually costs
7.6% 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 about an hour, 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 78.3% on time across 1,307 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 1,308 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 BWI 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. January runs 88.4% on time and July 63.5%, a swing of 25 points. If the dates move at all, move them out of July before you think about anything else. 1,281 completed flights over 12 months sit behind that.
Common questions
IAH to BWI questions
How often is IAH to BWI delayed?
Roughly one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 22.7% of the 1,308 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
How reliable is IAH to BWI compared with the rest of the country?
77.3% of flights arrive on time here against a national 77.3%, a difference of half 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 IAH to BWI?
The 11am–2pm departure window is the strongest at 86.4% on time. The 2pm–5pm window is the weakest at 52.2%, 34 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 BWI?
July is the weakest month at 63.5% on time, compared with 88.4% in January. 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
- BWI to IAH — the return legseparate record
- George Bush Intercontinental (IAH) delay statistics
- Baltimore/Washington International Thurgood Marshall (BWI) delay statistics
- United Airlines on IAH to BWI81.3%
- Spirit Airlines on IAH to BWI79.9%
- Frontier Airlines on IAH to BWI52.1%
- IAH to ORD, a related route75.1%
- ATL to BWI, a related route75.2%
- IAH to DFW, a related route76.4%
- SkyWest Airlines on-time record100.0%
- United Airlines on-time record81.3%
- Spirit Airlines on-time record79.9%
- The best time of day to fly, according to 7.05 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. IAH to BWI and BWI to IAH are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Embed IAH to BWI’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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.