PlainFlights

Route · IAH → SEA · 2020–2025 BTS data

Houston to Seattle

According to PlainFlights' route traffic ranking (BTS On-Time Performance total flights), IAH to SEA (Houston to Seattle) ranks #1075 of 4927 tracked domestic routes by total flights (most flights = #1).

Data updated 2026-06-13

79.8%
On-time
+0.8 pts
vs US avg
65 min
Delay when late
10,724
Flights
#1075 of 4927
Corpus placement

Cancelled

1.6%

Best Month

Feb 2024 91%

Worst Month

May 2024 61%

Distance

1,874 mi

Carriers

4

Monthly Performance

Recent 24 months of route data.

Period Flights Delayed Cancelled Diverted Carriers
Dec 2025 169 49 0 2 AS,UA
Nov 2025 148 33 0 0 UA,AS
Oct 2025 175 34 1 0 AS,UA
Sep 2025 199 28 0 0 UA,AS
Aug 2025 228 70 3 0 UA,AS
Jul 2025 236 76 4 1 AS,UA
Jun 2025 229 82 8 1 AS,UA
May 2025 187 51 2 0 AS,UA
Apr 2025 150 32 2 0 UA,AS
Mar 2025 150 32 1 0 AS,UA
Feb 2025 112 32 0 0 AS,UA
Jan 2025 130 27 5 2 AS,UA
Dec 2024 155 26 1 1 AS,UA
Nov 2024 142 19 0 0 UA,AS
Oct 2024 168 20 0 0 UA,AS
Sep 2024 204 26 0 2 UA,AS
Aug 2024 233 54 1 2 AS,UA
Jul 2024 248 88 12 1 AS,UA
Jun 2024 214 71 2 0 AS,UA
May 2024 214 83 6 0 AS,UA
Apr 2024 162 41 0 1 AS,UA
Mar 2024 149 27 1 0 AS,UA
Feb 2024 116 10 1 1 AS,UA
Jan 2024 140 35 20 0 AS,DL,UA

IAH–SEA seasonal on-time pattern

Best: September (87.0%) · weakest: June (71.3%)

70%75%80%85%90% JanFebMarAprMayJunJulAugSepOctNovDec 79.2%

Strongest calendar month

September

87.0% on-time · ~163 flights/mo

Busiest calendar month

July

~185 flights/mo avg

Weakest calendar month

June

71.3% on-time · ~159 flights/mo

Cancellation Rate

1.6%

70 of 4,258 flights

Diversion Rate

0.3%

14 of 4,258 flights

Explore origin & destination

On-time and delay data for the airports this route connects.

IAH - Houston

Full on-time, delay-cause, and seasonal performance for Houston, TX.

IAH on-time profile

SEA - Seattle

Full on-time, delay-cause, and seasonal performance for Seattle, WA.

SEA on-time profile

Compare the two airports

See IAH and SEA side by side on delays, cancellations, and reliability.

Compare IAH vs SEA

Origin-hub reliability standing

Mid-pack among IAH departures

From IAH, this corridor sits with 79 other 75–85% on-time routes out of 102 tracked departures, not the hub's reliability leaders (17 at ≥85%) and not the softest ( 6 below 75%). Destination: Seattle · fleet on-time rank #3225 of 4927.

What the Data Says About IAH to SEA

10,724 tracked flights put the IAH to SEA pairing (Houston to Seattle) at a 79.8% on-time rate, squarely in line with the wider network. Delays that do occur run 64.6 minutes on average. Across the 1,874-mile route and its 4 carriers, the trailing 24 months show 1.6% cancelled and 0.3% diverted (4,258 flights sampled).

The monthly split is wide on this route: Feb 2024 posted the strongest performance at 91% on-time, while May 2024 came in at just 61% - a 30-point swing worth factoring into travel timing.

On the multi-year calendar, IAH–SEA peaks in September at 87.0% on-time while July carries the heaviest traffic (~185 flights per month) ; the softest month is June at 71.3%, a 15.7-point swing that repeats because the corridor's weather and holiday mix stays stable year to year.

Frequently Asked Questions

Where does IAH to SEA rank among US routes by traffic? ▼
According to PlainFlights' route traffic ranking, IAH to SEA ranks #1075 of 4927 tracked domestic routes by total flights (most flights = #1). That ordinal matches our busiest-routes listing (total_flights DESC). See /methodology#corpus-placement for the exact sort basis.
How often are flights delayed from IAH to SEA? ▼
Flights from Houston to Seattle have a 79.8% on-time rate based on 10,724 flights. The average delay is 64.6 minutes. The best recent month was Feb 2024 with 91% on-time.
What is the cancellation rate for IAH to SEA? ▼
Over the last 24 months, 1.6% of flights on this route were cancelled (70 of 4,258 flights) and 0.3% were diverted.
How far is the flight from IAH to SEA? ▼
The flight distance from Houston (IAH) to Seattle (SEA) is approximately 1,874 miles. This route is served by 4 carriers.
When is the best time to fly from IAH to SEA? ▼
The best recent month for on-time performance was Feb 2024 (91% on-time). The worst was May 2024 (61% on-time). Consider booking during months with historically better performance.

Airports on this route

IAH Airport

Houston
SEA Airport

Seattle
Data source

Data Source: Bureau of Transportation Statistics (BTS), On-Time Performance Data. Statistics reflect cumulative performance across all available reporting periods.

Read our methodology - how this data is sourced, computed, and verified.

Using IAH–SEA data

IAH–SEA is mid-pack at 79.8% on-time; month and carrier mix move more than the corridor headline.

  • Compare IAH and SEA airport profiles: delay causes and top routes differ even on the same corridor. IAH airport
  • If your dates flex, September (87.0% on-time) beats June (71.3%) on this corridor. Seasonal chart
  • 4 other routes post a similar 79.8% on-time rate; compare before you commit to this pairing. Similar routes

On-time rate reflects the BTS historical average across all reporting carriers on this origin–destination pair, not any single flight or booking recommendation.

Data sourced from U.S. Department of Transportation Bureau of Transportation Statistics (BTS) On-Time Performance data. See our methodology for details. Retrieved and formatted by PlainFlights

Every figure on PlainFlights is rendered directly from BTS On-Time Performance data, no number is typed in by an editor. This page aggregates this specific route's on-time performance and monthly trend, live from the dataset. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.