Route on-time record
IAH to SEA: most on-time flights and the best time to fly
Houston (George Bush Intercontinental Airport) to Seattle (Seattle–Tacoma International Airport). 2,107 nonstop flights in Jun 2025 to May 2026, 76% arrived within 15 minutes and 0.9% were cancelled. The most reliable flight number was United 1351 at 8:00 AM.
Flying on a specific date? We’ll adjust for the month, the weekday and the forecast.
IAH → SEA
Houston to Seattle: 2,107 nonstop flights a year
On time (12 months)
76%
Cancelled
0.9%
avg delay 15 min
Best time to leave
Before 9 AM
86% on time vs 64% 6 to 9 PM
Most reliable airline
United
76% chance on time
Fares open on our travel partner (Aviasales). Pick the flight number you chose here.
Most reliable nonstop flights
Ranked by the chance the flight operates and arrives within 15 minutes of schedule, from Jun 2025 to May 2026 records.
#1 · United 1351
8:00 AM → 10:47 AM4h 47m nonstop
Local times, typical schedule. Last flown 2026-05-31.
85%
chance on time
- On time (history)
- 100%
- Cancelled
- 0.0%
- Avg arrival delay
- 1 min
- Arrived on time 100% of the time (11 flights, Jun 2025 to May 2026).
- Leaves in this route's most on-time window (Before 9 AM: 86% on time; 6 to 9 PM: 64%).
- Departs outside IAH's trouble window (noon to 6 PM, when 60% of its 92 ground stops and delay programs started).
- Short track record (11 flights), so its score leans on the airline's record at this hour.
Limited track record · 11 flights
Find United 1351 fares Opens this date on Aviasales#2 · Alaska 453
7:00 AM → 9:57 AM4h 57m nonstop
Local times, typical schedule. Last flown 2026-05-31.
84%
chance on time
- On time (history)
- 85%
- Cancelled
- 0.9%
- Avg arrival delay
- 9 min
- Arrived on time 85% of the time (343 flights, Jun 2025 to May 2026).
- Leaves in this route's most on-time window (Before 9 AM: 86% on time; 6 to 9 PM: 64%).
- Departs outside IAH's trouble window (noon to 6 PM, when 60% of its 92 ground stops and delay programs started).
Strong track record · 343 flights
Find Alaska 453 fares Opens this date on Aviasales#3 · United 366
10:02 AM → 1:07 PM5h 05m nonstop
Local times, typical schedule. Last flown 2026-03-28.
83%
chance on time
- On time (history)
- 88%
- Cancelled
- 0.0%
- Avg arrival delay
- 7 min
- Arrived on time 88% of the time (24 flights, Jun 2025 to May 2026).
- Departs outside IAH's trouble window (noon to 6 PM, when 60% of its 92 ground stops and delay programs started).
- Short track record (24 flights), so its score leans on the airline's record at this hour.
Limited track record · 24 flights
Find United 366 fares Opens this date on Aviasales#4 · United 2205
9:50 AM → 12:47 PM4h 56m nonstop
Local times, typical schedule. Last flown 2026-05-31.
80%
chance on time
- On time (history)
- 88%
- Cancelled
- 0.0%
- Avg arrival delay
- 10 min
- Arrived on time 88% of the time (64 flights, Jun 2025 to May 2026).
- Never cancelled in 64 scheduled flights.
- Departs outside IAH's trouble window (noon to 6 PM, when 60% of its 92 ground stops and delay programs started).
- 59% of its delay minutes came from the plane arriving late from an earlier flight.
Moderate track record · 64 flights
Find United 2205 fares Opens this date on Aviasales#5 · United 683
4:25 PM → 7:25 PM5h 00m nonstop
Local times, typical schedule. Last flown 2026-03-27.
80%
chance on time
- On time (history)
- 82%
- Cancelled
- 0.0%
- Avg arrival delay
- 26 min
- Arrived on time 82% of the time (17 flights, Jun 2025 to May 2026).
- Departs inside IAH's trouble window: 60% of its 92 ground stops and delay programs started between noon and 6 PM.
- Lands inside SEA's trouble window: 54% of its 68 ground stops and delay programs started between 4 PM and 10 PM.
- Short track record (17 flights), so its score leans on the airline's record at this hour.
Limited track record · 17 flights
Find United 683 fares Opens this date on Aviasales#6 · Alaska 241
8:00 AM → 10:53 AM4h 53m nonstop
Local times, typical schedule. Last flown 2026-05-31.
80%
chance on time
- On time (history)
- 84%
- Cancelled
- 0.0%
- Avg arrival delay
- 8 min
- Arrived on time 84% of the time (19 flights, Jun 2025 to May 2026).
- Leaves in this route's most on-time window (Before 9 AM: 86% on time; 6 to 9 PM: 64%).
- Departs outside IAH's trouble window (noon to 6 PM, when 60% of its 92 ground stops and delay programs started).
- Short track record (19 flights), so its score leans on the airline's record at this hour.
Limited track record · 19 flights
Find Alaska 241 fares Opens this date on Aviasales#7 · United 515
8:15 PM → 11:12 PM4h 57m nonstop
Local times, typical schedule. Last flown 2026-04-29.
79%
chance on time
- On time (history)
- 93%
- Cancelled
- 0.0%
- Avg arrival delay
- 4 min
- Arrived on time 93% of the time (29 flights, Jun 2025 to May 2026).
- Leaves in this route's least on-time window (6 to 9 PM: 64% on time; Before 9 AM: 86%).
- Departs outside IAH's trouble window (noon to 6 PM, when 60% of its 92 ground stops and delay programs started).
- Short track record (29 flights), so its score leans on the airline's record at this hour.
Limited track record · 29 flights
Find United 515 fares Opens this date on Aviasales#8 · United 2638
4:45 PM → 7:44 PM4h 59m nonstop
Local times, typical schedule. Last flown 2026-05-31. Same departure also flew as United 1606; its record covers all of them.
77%
chance on time
- On time (history)
- 84%
- Cancelled
- 0.0%
- Avg arrival delay
- 11 min
- Arrived on time 84% of the time (64 flights, Jun 2025 to May 2026).
- Never cancelled in 64 scheduled flights.
- Departs inside IAH's trouble window: 60% of its 92 ground stops and delay programs started between noon and 6 PM.
- Lands inside SEA's trouble window: 54% of its 68 ground stops and delay programs started between 4 PM and 10 PM.
Moderate track record · 64 flights
Find United 2638 fares Opens this date on Aviasales#9 · United 1795
6:05 PM → 8:53 PM4h 48m nonstop
Local times, typical schedule. Last flown 2026-05-31.
72%
chance on time
- On time (history)
- 100%
- Cancelled
- 0.0%
- Avg arrival delay
- 4 min
- Arrived on time 100% of the time (8 flights, Jun 2025 to May 2026).
- Leaves in this route's least on-time window (6 to 9 PM: 64% on time; Before 9 AM: 86%).
- Departs outside IAH's trouble window (noon to 6 PM, when 60% of its 92 ground stops and delay programs started).
- Lands inside SEA's trouble window: 54% of its 68 ground stops and delay programs started between 4 PM and 10 PM.
Limited track record · 8 flights
Find United 1795 fares Opens this date on Aviasales#10 · United 2456
7:57 PM → 10:59 PM4h 57m nonstop
Local times, typical schedule. Last flown 2026-05-31.
67%
chance on time
- On time (history)
- 67%
- Cancelled
- 1.5%
- Avg arrival delay
- 19 min
- Arrived on time 67% of the time (322 flights, Jun 2025 to May 2026).
- Leaves in this route's least on-time window (6 to 9 PM: 64% on time; Before 9 AM: 86%).
- Departs outside IAH's trouble window (noon to 6 PM, when 60% of its 92 ground stops and delay programs started).
Strong track record · 322 flights
Find United 2456 fares Opens this date on Aviasales
Airlines on this route
Season-adjusted chance of operating and arriving on time.
- United Airlines76%
1,252 flights · 76% on time as flown · 0.7% cancel
- Alaska Airlines76%
855 flights · 77% on time as flown · 1.1% cancel
On time by departure time
All airlines, scheduled local departure, Jun 2025 to May 2026.
- Before 9 AM86%
480 flights · avg delay 8 min
- 9 AM to noon82%
445 flights · avg delay 10 min
- 3 to 6 PM80%
319 flights · avg delay 16 min
- 6 to 9 PM64%
789 flights · avg delay 22 min
Best day: Tuesday (81%). Worst: Sunday (75%).
On time by month
All airlines, Jun 2023 to May 2026. Several years per month, so one stormy season doesn't define a month. Travel-month estimates use this seasonal pattern.
What delays this route
- Late-arriving aircraft41%
- Airline (crew, maintenance, boarding)30%
- Air traffic control and airport volume23%
- Severe weather5%
Share of delay minutes by the cause airlines report to the US DOT.
Historical odds, not a guarantee. Built from the US DOT Bureau of Transportation Statistics on-time reports (Jun 2025 to May 2026), FAA ground stop and delay program advisories, and 20 years of airport weather observations. Covers US airlines that report to the DOT; schedules are flights operated recently, so confirm times when you book. ATIS Alerts is not affiliated with any airline. Fares are what Aviasales travelers saw in recent searches (USD, one way, 1 adult), not live quotes; the partner site shows the current price. Fare links go to our travel partner and may earn us a commission at no cost to you. Affiliate disclosure
IAH to SEA questions
- What time of day is best to fly IAH to SEA?
- Before 9 AM: 86% of flights arrived on time, against 64% for departures 6 to 9 PM. Later flights inherit delays from earlier ones, so the first departures of the day usually run best.
- Which airline is most on time from IAH to SEA?
- United, with a season-adjusted 76% chance of operating and arriving on time over 1,252 flights. The adjustment compares each airline with what the route did in the months it flew, so a carrier that skipped a stormy month gets no free credit.
- What is the worst month for delays on IAH to SEA?
- June (66% on time); the best was September (84%), averaged over Jun 2023 to May 2026.
- Is this a prediction for my flight?
- No. These are historical odds from the US DOT on-time reports, FAA advisories and airport weather records. Check your flight status and the FAA delay board on the day you fly.
More routes from IAH
- SEA to IAH (return)
- IAH to ORD 75%
- IAH to DFW 75%
- IAH to LAX 83%
- IAH to ATL 77%
- IAH to DEN 81%
- IAH to LGA 72%
- IAH to MIA 78%
- IAH to EWR 74%
- IAH to MCO 81%
- IAH to SFO 79%
- IAH to LAS 82%
- IAH to DCA 75%
Live status: FAA delays and ground stops