Route profile
SEA→IAH
Flight reliability, delays and best times to fly from Seattle to Houston, 1,874 miles.
Right now
Aviation weather is not currently a factor.
Aviation weather is not currently a factor.
Route reliability
July 2023 – July 2026
Better than 66% of comparable major US routes (4,598 compared)
Calculated from 6,529 flights. How this is calculated
SEA → IAH arrives on time 79.4% of the time; the return trip, IAH → SEA, arrives on time 77.4% of the time, a 2.0-point gap between the two directions of the same city pair.
SEA → IAH spends 31.9 minutes on the ground on a 1,874-mile trip: 20.7 minutes from pushback to wheels-up at SEA and 11.2 minutes from touchdown to gate at IAH.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What sets this route apart
Where SEA to IAH differs most from similar routes by hour, weekday, month and airline, July 2023 – July 2026.
SEA to IAH struggles most at 11 AM: 68.4% of its flights scheduled then arrive on time, 9.2 points behind the 77.6% on routes of similar length at the same hour. Against all other routes the gap is 12.6 points.
SEA to IAH is at its best against routes of similar length for flights scheduled at 1 PM: 83.3% arrive on time, 9.1 points ahead of the 74.2% those routes manage at that hour. Against all other routes the gap is 6.2 points.
SEA to IAH holds up on Mondays better than routes of similar length do: 80.2% on time to their 77.3%, a 2.9 points lead. Against all other routes the gap is 3 points.
February is kinder to SEA to IAH than to routes of similar length: 90.3% on time against 81.2%, 9.1 points better. Against all other routes the gap is 8.9 points.
United Airlines does better on SEA to IAH than on its routes of similar length: 83.3% on time here, 80.0% there, 3.3 points apart. Against all other routes the gap is 3.4 points.
SEA to IAH against comparable routes
July 2023 – July 2026| Measure | This route | Compared with | Them | Gap | Flights behind it |
|---|---|---|---|---|---|
| Hour: 11 AM departures | 68.4% | routes of similar length | 77.6% | −9.2 pts | 813 here, 67,568 there |
| Hour: 1 PM departures | 83.3% | routes of similar length | 74.2% | +9.1 pts | 264 here, 58,864 there |
| Weekday: Monday | 80.2% | routes of similar length | 77.3% | +2.9 pts | 922 here, 172,234 there |
| Month: February | 90.3% | routes of similar length | 81.2% | +9.1 pts | 339 here, 77,949 there |
| Airline: United Airlines | 83.3% | routes of similar length | 80.0% | +3.3 pts | 3,744 here, 252,504 there |
Each comparison pools the flights of other routes, with this route’s own left out. Similar length means within 15% of this route’s 1,874 miles, with at least 5 such routes. A bucket is set against the most comparable group that has enough flights: similar length, then the same origin (at least 3 routes), then all other routes. Hours, weekdays and months appear only where both sides have 120 completed flights, and airlines where both have 600. The gap must be at least 2 points and 2 standard errors, and only the largest gap each way is kept per measure. These are differences in the flights counted, not causes.
Why SEA → IAH flights are cancelled
July 2023 – July 2026
SEA → IAH cancelled 79 of 6,529 scheduled flights — about 1 in every 83. The reason filed most often was the airline, 62.0% of the cancellations coded on this route — about 1 in every 133 scheduled flights.
Share of cancellations
Of 79 cancelled departures carrying a reason code.
What each reason means
Crew, maintenance, aircraft cleaning, baggage or fueling: what BTS counts as within the carrier’s own control.
49 cancellations, 62.0% of the total.
Conditions the carrier judged severe enough to stop the flight: a blizzard, a hurricane, a line of thunderstorms.
25 cancellations, 31.6% of the total.
Airport capacity, air traffic control flow programs, heavy traffic and ordinary bad weather. A system decision, not the airline’s.
5 cancellations, 6.3% of the total.
A terminal evacuation, a security breach, screening equipment failure, or screening queues over 29 minutes.
0 cancellations, 0.0% of the total.
Reason codes are the operating airline’s own filing with US DOT, not an independent finding of fault. With only one or two carriers on the route, the split mostly reflects how they file. Ordinary bad weather is filed under air traffic, so weather’s full share is larger than its bar.
79 coded cancellations were recorded on SEA → IAH; the section appears from 50.
When it goes wrong
July 2023 – July 2026
35 min late
against a median of 5 min early
Percentiles over 6,529 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at IAH after arriving from SEA.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 40% | Likely to miss |
| 45 min | 20% | High risk |
| 60 min | 12% | Some risk |
| 90 min | 4.7% | Low risk |
| 120 min | 2.9% | Low risk |
This is one leg of a connection. Gate changes and the next flight's own schedule matter too. And a connection can fail before delay is even the question — this route cancels 1.21% of the time and diverts 0.37% of the time, which a late arrival never shows up in.
Chance of missing is the share of 6,426 arrivals on this route that landed later than the connection time less 30 minutes to reach the next gate.
The worst tenth of arrivals on this route land at least 35 minutes late (90th-percentile gate arrival delay), over 6,529 operations.
Any other layover length: connection checker.
Best time to fly
SEA → IAH flights departing 5–9 AM arrived on time 88.1% of the time, against 72.5% for 9 AM–12 PM departures, a gap of 15.6 percentage points.
By departure window
By departure hour
- 12 AM to 4 AM: too few flights to score
- 5 AM: 87.0% on time from 196 flights
- 6 AM: too few flights to score
- 7 AM: 87.9% on time from 968 flights
- 8 AM to 9 AM: too few flights to score
- 10 AM: 75.6% on time from 552 flights
- 11 AM: 68.4% on time from 825 flights
- 12 PM: 75.2% on time from 305 flights
- 1 PM: 83.3% on time from 266 flights
- 2 PM: 82.5% on time from 294 flights
- 3 PM to 4 PM: too few flights to score
- 5 PM: 76.8% on time from 1,098 flights
- 6 PM to 10 PM: too few flights to score
- 11 PM: 79.6% on time from 1,647 flights
Departure windows with fewer than 120 flights are not scored.
Why SEA → IAH runs late
July 2023 – July 2026
crew, maintenance, boarding and fueling, all within the carrier’s control
the inbound aircraft was late, so this flight started late
airspace and airport capacity, including weather-driven flow control
weather severe enough to stop this flight specifically
screening or terminal security incidents
Share of the delay minutes US DOT attributed to each cause for SEA → IAH. Only delays of 15 minutes or more are attributed.
Airlines on this route
Carriers with at least 200 flights, by the airline that operated each one.
| Carrier | Flights | On time | Cancelled | Median delay | Severe |
|---|---|---|---|---|---|
| United Airlines | 3,807 | 83.3% | 1.21% | -7 min | 5.1% |
| Alaska Airlines | 2,719 | 73.9% | 1.21% | -1 min | 4.3% |
United Airlines flew 58.3% of the 6,526 flights listed.
United Airlines arrived on time 9.4 percentage points more often than Alaska Airlines on this route.
Flights on this route
Flight numbers with at least 600 operations here and still on the schedule.
Weekly and seasonal patterns
By day of week
Wednesday is historically the most reliable day and Friday the least, a gap of 7.8 percentage points.
By month
- Jan: 81.7%
- Feb: 90.3%
- Mar: 80.4%
- Apr: 81.5%
- May: 77.5%
- Jun: 74.3%
- Jul: 71.4%
- Aug: 74.1%
- Sep: 84.6%
- Oct: 85.9%
- Nov: 83.0%
- Dec: 81.3%
July is historically the weakest month and February the strongest, a spread of 18.9 percentage points.
Reliability over time
July 2023 – July 2026
- July 2023: 70.8% from 212 flights
- August 2023: 78.8% from 213 flights
- September 2023: 77.3% from 178 flights
- October 2023: 84.5% from 182 flights
- November 2023: 85.5% from 159 flights
- December 2023: 89.7% from 155 flights
- January 2024: 76.9% from 141 flights
- February 2024: too few flights to score (116)
- March 2024: 79.2% from 150 flights
- April 2024: 79.1% from 163 flights
- May 2024: 73.4% from 214 flights
- June 2024: 74.1% from 213 flights
- July 2024: 69.5% from 248 flights
- August 2024: 75.0% from 233 flights
- September 2024: 86.3% from 204 flights
- October 2024: 91.1% from 168 flights
- November 2024: 81.6% from 142 flights
- December 2024: 79.7% from 155 flights
- January 2025: 83.9% from 130 flights
- February 2025: too few flights to score (112)
- March 2025: 81.2% from 150 flights
- April 2025: 78.9% from 150 flights
- May 2025: 74.6% from 187 flights
- June 2025: 63.9% from 228 flights
- July 2025: 63.6% from 236 flights
- August 2025: 68.8% from 228 flights
- September 2025: 89.4% from 198 flights
- October 2025: 82.3% from 176 flights
- November 2025: 81.8% from 148 flights
- December 2025: 75.0% from 168 flights
- January 2026: 84.2% from 134 flights
- February 2026: too few flights to score (112)
- March 2026: 80.9% from 144 flights
- April 2026: 86.7% from 150 flights
- May 2026: 85.2% from 184 flights
- June 2026: 85.1% from 217 flights
- July 2026: 81.7% from 231 flights
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 82.3% against 77.5% in the 12 months before — improving by 4.8 percentage points.
Data and methodology
Calculated by FlyerIntel from 6,529 SEA → IAH flight records from the US DOT Bureau of Transportation Statistics, covering July 2023 – July 2026. Late means 15 or more minutes past scheduled arrival; cancelled and diverted flights are left out of on-time rates.
Full methodology · Data sources · Report a problem
Related research: How Long a Layover Needs to Be · Two Airlines on One Route · Best Time of Day to Fly From Major US Airports
Analysis last recomputed