BTS DATA COMPLETE THROUGH JUNE 2026HISTORICAL ODDS · NOT LIVE FLIGHT STATUS
DelayOddsKnow the route before you book
IAD→SEA

Washington, DC (IAD) to Seattle, WA (SEA) flight delay odds

75.6% of 1,884 official scheduled IAD-to-SEA flights arrived on time; 13.8% arrived at least 30 minutes late and 1.0% were cancelled during July 2025–June 2026.

Source: U.S. Bureau of Transportation Statistics · Reporting window: July 2025–June 2026 · Updated September 16, 2026

HISTORICAL ROUTE SIGNALGenerally reliable
75.6%arrived on time
13.8%30+ min late
1.0%cancelled
1,884scheduled flights
Based on July 2025–June 2026; on time means arrival less than 15 minutes late.
60+ minutes late7.0%all scheduled flights
120+ minutes late2.7%all scheduled flights
Diverted0.2%did not reach as scheduled
Average arrival+6.3 mincompleted flights

Which departure time was most reliable for IAD to SEA?

Among qualifying IAD-to-SEA departure window results, Afternoon had the highest on-time rate: 91.5% of 165 flights. Evening was lowest at 66.5% across 680 flights.

Departure windowFlightsOn time30+ minCancelled
Early morning72977.9%12.5%1.0%
Late morning26384.4%7.6%0.8%
Afternoon16591.5%6.1%0.0%
Evening68066.5%19.1%1.3%
Night4768.1%19.1%2.1%

Which weekday was most reliable for IAD to SEA?

Among qualifying IAD-to-SEA weekday results, Saturday had the highest on-time rate: 77.4% of 261 flights. Sunday was lowest at 71.9% across 278 flights.

DayFlightsOn time30+ minCancelled
Monday28076.8%14.6%0.4%
Tuesday25874.4%13.6%0.4%
Wednesday25176.9%13.9%0.8%
Thursday27776.5%12.3%0.7%
Friday27975.6%11.8%0.4%
Saturday26177.4%11.5%1.5%
Sunday27871.9%18.7%2.9%

Which airline was most reliable for IAD to SEA?

Among qualifying IAD-to-SEA airline results, United Airlines had the highest on-time rate: 78.9% of 688 flights. Alaska Airlines was lowest at 72.8% across 835 flights.

AirlineFlightsOn time30+ minCancelled
Alaska Airlines83572.8%15.1%1.2%
United Airlines68878.9%12.4%0.6%
Delta Air Lines36175.9%13.6%1.4%

Which month was most reliable for IAD to SEA?

Among qualifying IAD-to-SEA month results, September 2025 had the highest on-time rate: 92.2% of 179 flights. December 2025 was lowest at 47.6% across 124 flights.

MonthFlightsOn time30+ minCancelled
July 202524572.7%20.0%0.8%
August 202522180.1%9.5%0.5%
September 202517992.2%4.5%0.0%
October 202515683.3%10.9%1.3%
November 202511967.2%16.0%2.5%
December 202512447.6%29.8%0.8%
January 202610371.8%18.4%2.9%
February 20269374.2%11.8%2.2%
March 202611753.0%25.6%0.9%
April 202612882.0%8.6%0.8%
May 202620186.1%6.5%0.0%
June 202619877.3%12.6%1.5%

What drove IAD to SEA delay minutes?

Airline was the largest recorded IAD-to-SEA delay category, accounting for 41.7% of 27,433 BTS-attributed delay minutes during July 2025–June 2026.

Airline41.7%
Late aircraft17.1%
National airspace31.0%
Weather9.5%
Security0.7%
This is historical evidence, not a forecast.

Weather, schedules and operations change. For a trip you have already booked, use the airline or airport for live status.