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

Boston, MA (BOS) to Seattle, WA (SEA) flight delay odds

70.3% of 2,461 official scheduled BOS-to-SEA flights arrived on time; 15.7% arrived at least 30 minutes late and 1.3% 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
70.3%arrived on time
15.7%30+ min late
1.3%cancelled
2,461scheduled flights
Based on July 2025–June 2026; on time means arrival less than 15 minutes late.
60+ minutes late7.1%all scheduled flights
120+ minutes late2.7%all scheduled flights
Diverted0.4%did not reach as scheduled
Average arrival+7.2 mincompleted flights

Which departure time was most reliable for BOS to SEA?

Among qualifying BOS-to-SEA departure window results, Afternoon had the highest on-time rate: 77.3% of 203 flights. Evening was lowest at 59.2% across 807 flights.

Departure windowFlightsOn time30+ minCancelled
Early morning88675.1%11.3%1.2%
Late morning56575.9%11.3%0.7%
Afternoon20377.3%15.3%0.5%
Evening80759.2%23.7%1.9%

Which weekday was most reliable for BOS to SEA?

Among qualifying BOS-to-SEA weekday results, Wednesday had the highest on-time rate: 74.6% of 346 flights. Thursday was lowest at 63.8% across 359 flights.

DayFlightsOn time30+ minCancelled
Monday36173.1%13.6%2.5%
Tuesday35570.1%15.5%1.4%
Wednesday34674.6%14.7%1.2%
Thursday35963.8%19.5%0.8%
Friday35970.2%15.0%0.6%
Saturday32073.1%14.1%0.9%
Sunday36167.3%17.2%1.4%

Which airline was most reliable for BOS to SEA?

Among qualifying BOS-to-SEA airline results, JetBlue Airways had the highest on-time rate: 75.3% of 247 flights. Alaska Airlines was lowest at 69.2% across 1,208 flights.

AirlineFlightsOn time30+ minCancelled
Alaska Airlines1,20869.2%16.6%1.2%
Delta Air Lines1,00670.3%14.2%1.6%
JetBlue Airways24775.3%17.0%0.4%

Which month was most reliable for BOS to SEA?

Among qualifying BOS-to-SEA month results, September 2025 had the highest on-time rate: 83.8% of 229 flights. December 2025 was lowest at 37.3% across 161 flights.

MonthFlightsOn time30+ minCancelled
July 202527459.9%21.2%2.2%
August 202527183.0%9.2%0.0%
September 202522983.8%11.4%0.0%
October 202522878.9%12.3%0.9%
November 202516377.3%11.0%0.6%
December 202516137.3%31.7%1.9%
January 202613166.4%18.3%4.6%
February 202612870.3%12.5%6.2%
March 202617239.5%31.4%0.0%
April 202617276.7%9.3%0.6%
May 202625478.7%11.4%0.4%
June 202627873.7%14.7%1.1%

What drove BOS to SEA delay minutes?

Late aircraft was the largest recorded BOS-to-SEA delay category, accounting for 38.2% of 37,321 BTS-attributed delay minutes during July 2025–June 2026.

Airline25.2%
Late aircraft38.2%
National airspace34.0%
Weather2.4%
Security0.1%
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.