Houston (IAH) to Seattle (SEA): On-Time Performance
Data through May 2026
When you fly IAH to SEA matters as much as anything else about the booking: the route swung from 91% on-time in April 2026 to just 62% in July 2024. Across the full period the route averages 76% on-time against a national 78%. Morning departures also hold up better than evening ones (84% vs 65%), which matters most in the rough months.
- On-time
- 76%
- arrived <15 min late
- Avg delay
- 15 min
- completed flights
- Cancelled
- 1.1%
- Flights/day
- 5.8
- last 12 months
- Duration
- 4h 51m
- scheduled
- Distance
- 1,874 mi
Best airline from IAH to SEA
2 airlines flew this route regularly between 2024-06 and 2026-05.
| Airline | On-time | Avg delay | Cancelled | Flights |
|---|---|---|---|---|
| Alaska Airlinesmost reliable | 77% | 13 min | 1.4% | 1,705 |
| United Airlines | 76% | 17 min | 0.8% | 2,495 |
Monthly on-time trend
Best time to fly from IAH to SEA
Aim for departures around 2 p.m. (89% on-time); avoid 8 p.m. departures (62%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Monday | 74% | 18 min |
| Tuesdaybest | 83% | 10 min |
| Wednesday | 75% | 15 min |
| Thursday | 76% | 15 min |
| Friday | 76% | 16 min |
| Saturday | 76% | 16 min |
| Sunday | 76% | 15 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft41%
- Airline operations32%
- National airspace system22%
- Weather5%
Frequently asked questions
- How often are flights from IAH to SEA delayed?
- 24% of IAH–SEA flights arrived 15 or more minutes late (the US DOT definition of a delay) between 2024-06 and 2026-05. The average arrival delay across completed flights was 15 minutes.
- Which airline is most reliable from IAH to SEA?
- Alaska Airlines has the best on-time record on this route at 77%, based on 1,705 flights. 2 airlines flew IAH–SEA frequently enough to compare in this period.
- What is the best time of day to fly from IAH to SEA?
- Departures around 2 p.m. have the best record (89% on-time), while departures around 8 p.m. have the worst (62%). As on most US routes, delays accumulate through the day, so earlier flights are generally safer.
- How long is the flight from IAH to SEA?
- The scheduled IAH–SEA flight time averages 4h 51m over 1,874 miles. Actual arrival times vary — flights on this route land 15+ minutes late 24% of the time.
- How often are IAH to SEA flights cancelled?
- 1.1% of scheduled flights on this route were cancelled between 2024-06 and 2026-05, at or below the national rate of 1.6%.
- What is the worst month to fly from IAH to SEA?
- July 2024 was the roughest month in this dataset, with only 62% of arrivals on time. The best was April 2026 at 91%. If your dates are flexible, that 28-point gap is worth planning around.
Explore related pages
More routes from IAH
Based on 4,200 flights, 2024-06–2026-05. Source: US DOT Bureau of Transportation Statistics. Updated 2026-07-01.