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

San Francisco, CA (SFO) to Boston, MA (BOS) flight delay odds

Historically, 75.7% of scheduled reportable flights on this direction arrived on time in July 2025–June 2026. The sample includes 4,674 flights.

HISTORICAL ROUTE SIGNALGenerally reliable
75.7%arrived on time
15.5%30+ min late
1.3%cancelled
4,674scheduled flights
Based on July 2025–June 2026; on time means arrival less than 15 minutes late.
60+ minutes late9.1%all scheduled flights
120+ minutes late3.6%all scheduled flights
Diverted0.1%did not reach as scheduled
Average arrival+6.5 mincompleted flights

When is this route most reliable?

The same route can behave differently through the day. These are scheduled departure windows, not actual departure times. Small time windows with fewer than 40 flights are withheld.

Departure windowFlightsOn time30+ minCancelled
Early morning1,39683.5%10.3%1.0%
Late morning63364.3%25.8%0.6%
Afternoon1,43572.6%17.4%2.0%
Evening15580.0%14.8%2.6%
Night1,05575.9%13.8%1.2%

Weekday comparison

Day-of-week results use at least 30 scheduled flights per row. Look for broad patterns, not tiny percentage differences.

DayFlightsOn time30+ minCancelled
Monday71072.1%18.0%2.5%
Tuesday66478.0%14.9%1.1%
Wednesday64877.0%15.4%0.2%
Thursday69870.1%20.6%0.3%
Friday70576.6%15.9%0.7%
Saturday55083.6%9.8%0.7%
Sunday69974.7%12.7%3.7%

Airline comparison

Marketing-carrier results make codeshare flights easier to compare as travelers buy them. Dedicated route-airline reports require at least 160 flights.

AirlineFlightsOn time30+ minCancelled
United Airlines1,86678.1%14.8%1.0%
JetBlue Airways1,67474.0%17.3%1.8%
Delta Air Lines89973.7%14.9%1.4%
Alaska Airlines23476.9%10.3%0.4%
Southwest Airlines10.0%100.0%0.0%

Monthly trend

Month-by-month results show whether a twelve-month average hides an unusual period.

MonthFlightsOn time30+ minCancelled
July 202545075.8%15.8%0.2%
August 202543184.5%7.7%0.2%
September 202540872.1%21.1%0.0%
October 202542870.1%22.9%0.7%
November 202536076.1%14.7%2.8%
December 202535681.2%12.9%0.6%
January 202631377.3%14.1%5.4%
February 202628377.7%9.5%8.1%
March 202632377.7%17.0%0.3%
April 202638176.4%15.5%0.3%
May 202643975.4%14.4%0.0%
June 202650268.3%18.1%0.8%

What drove reported delay minutes?

BTS cause minutes are reported for qualifying delayed flights. These shares describe recorded delay minutes—not the chance that a particular cause will affect your next flight.

Airline22.3%
Late aircraft36.6%
National airspace38.6%
Weather2.6%
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.