Houston (IAH) to Seattle (SEA): On-Time Performance
Data through July 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 77% on-time against a national 78%. Morning departures also hold up better than evening ones (85% vs 66%), which matters most in the rough months.
- On-time
- 77%
- arrived <15 min late
- Avg delay
- 15 min
- completed flights
- Cancelled
- 1.0%
- Flights/day
- 5.7
- last 12 months
- Duration
- 4h 51m
- scheduled
- Distance
- 1,874 mi
Best airline from IAH to SEA
2 airlines flew this route regularly between 2024-07 and 2026-07.
| Airline | On-time | Avg delay | Cancelled | Flights |
|---|---|---|---|---|
| Alaska Airlinesmost reliable | 78% | 13 min | 1.3% | 1,794 |
| United Airlines | 76% | 16 min | 0.8% | 2,640 |
Monthly on-time trend
Best time to fly from IAH to SEA
Aim for departures around 6 a.m. (89% on-time); avoid 5 p.m. departures (65%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Monday | 76% | 17 min |
| Tuesdaybest | 83% | 11 min |
| Wednesday | 77% | 13 min |
| Thursday | 77% | 15 min |
| Friday | 76% | 16 min |
| Saturday | 76% | 16 min |
| Sunday | 76% | 14 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft40%
- Airline operations33%
- National airspace system22%
- Weather5%
Frequently asked questions
- How often are flights from IAH to SEA delayed?
- 23% of IAH–SEA flights arrived 15 or more minutes late (the US DOT definition of a delay) between 2024-07 and 2026-07. 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 78%, based on 1,794 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 6 a.m. have the best record (89% on-time), while departures around 5 p.m. have the worst (65%). 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 23% of the time.
- How often are IAH to SEA flights cancelled?
- 1% of scheduled flights on this route were cancelled between 2024-07 and 2026-07, 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
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Based on 4,434 flights, 2024-07–2026-07. Source: US DOT Bureau of Transportation Statistics. Updated 2026-09-28.