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

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

73.3% of 2,459 official scheduled SEA-to-BOS flights arrived on time; 14.9% arrived at least 30 minutes late and 1.1% 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
73.3%arrived on time
14.9%30+ min late
1.1%cancelled
2,459scheduled flights
Based on July 2025–June 2026; on time means arrival less than 15 minutes late.
60+ minutes late7.8%all scheduled flights
120+ minutes late2.7%all scheduled flights
Diverted0.5%did not reach as scheduled
Average arrival+8.4 mincompleted flights

Which departure time was most reliable for SEA to BOS?

Among qualifying SEA-to-BOS departure window results, Early morning had the highest on-time rate: 81.2% of 681 flights. Late morning was lowest at 57.7% across 414 flights.

Departure windowFlightsOn time30+ minCancelled
Early morning68181.2%9.5%1.6%
Late morning41457.7%27.5%0.7%
Afternoon62073.7%15.0%1.0%
Night74474.3%12.6%1.1%

Which weekday was most reliable for SEA to BOS?

Among qualifying SEA-to-BOS weekday results, Tuesday had the highest on-time rate: 76.9% of 350 flights. Sunday was lowest at 69.4% across 359 flights.

DayFlightsOn time30+ minCancelled
Monday36171.2%15.8%1.9%
Tuesday35076.9%12.9%0.6%
Wednesday34974.5%14.0%0.3%
Thursday36071.7%16.9%0.8%
Friday36073.9%14.2%0.8%
Saturday32075.9%11.9%0.6%
Sunday35969.4%18.1%2.8%

Which airline was most reliable for SEA to BOS?

Among qualifying SEA-to-BOS airline results, Delta Air Lines had the highest on-time rate: 79.4% of 1,005 flights. JetBlue Airways was lowest at 50.6% across 247 flights.

AirlineFlightsOn time30+ minCancelled
Alaska Airlines1,20772.8%14.5%1.0%
Delta Air Lines1,00579.4%10.2%1.5%
JetBlue Airways24750.6%35.6%0.4%

Which month was most reliable for SEA to BOS?

Among qualifying SEA-to-BOS month results, March 2026 had the highest on-time rate: 86.0% of 172 flights. July 2025 was lowest at 58.4% across 274 flights.

MonthFlightsOn time30+ minCancelled
July 202527458.4%26.6%1.5%
August 202527064.4%20.4%0.0%
September 202522967.2%18.3%0.0%
October 202522771.8%18.1%0.9%
November 202516479.3%9.1%0.6%
December 202516185.1%5.0%1.2%
January 202612980.6%8.5%5.4%
February 202612976.0%10.9%5.4%
March 202617286.0%7.6%0.6%
April 202617275.6%15.1%0.6%
May 202625482.7%9.1%0.4%
June 202627869.8%16.2%0.7%

What drove SEA to BOS delay minutes?

Airline was the largest recorded SEA-to-BOS delay category, accounting for 36.4% of 41,955 BTS-attributed delay minutes during July 2025–June 2026.

Airline36.4%
Late aircraft26.2%
National airspace31.8%
Weather5.6%
Security0.0%
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.