Historical on-time performance
Boston to San Francisco
2,704 miData through May 2026Source: US DOT · BTS
Flights on BOS–SFO arrive on time 74% of the time over the last 12 months.
On-time rate74%arrived within 15 min
p90 delay50 min1 in 10 flights is worse (tail risk)
Cancelled1.1%of scheduled flights
based on 4,579 flights over the last 12 months. On-time means arriving within 15 minutes (BTS standard).
By airline
How each carrier compares
- United AirlinesbestOn-time78%Medianon timep9040 minCancel1.0%Flights1,816
- Delta Air LinesOn-time73%Medianon timep9040 minCancel1.4%Flights882
- JetBlue AirwaysOn-time72%Medianon timep9050 minCancel1.2%Flights1,619
- Alaska AirlinesOn-time64%Medianon timep9065 minCancel0.4%Flights262
Why flights run late
Delay causes
- Airline26%
- Weather2%
- Air traffic (NAS)34%
- Late aircraft38%
- Security0%
Most delay minutes here are attributed to Late aircraft.
When flights don't go
Why flights were cancelled
- Airline17%
- Weather71%
- Air traffic (NAS)12%
- Security0%
Most cancellations here are attributed to Weather. Shares are among 52 cancellations with a reported cause (BTS reports causes from June 2003).
Over time
On-time trend
By season
On-time rate by month
When to fly
Best time to fly BOS → SFO
All airlines · rolling 36 months (2023-06 .. 2026-05).
Best time of day
Mornings are the most reliable time of day to fly this route — 83% on time.
- Mornings83% on time · p90 25 min · 5,267 flights
- Middays81% on time · p90 40 min · 2,406 flights
- Afternoons70% on time · p90 60 min · 1,174 flights
- Evenings66% on time · p90 75 min · 3,363 flights
- Overnights60% on time · p90 80 min · 1,438 flights
Best day of week
On-time rates are fairly even by day on this route — ranging from 71% to 80% on time.
- Tuesdays80% on time · p90 30 min · 1,897 flights
- Wednesdays78% on time · p90 40 min · 1,918 flights
- Saturdays76% on time · p90 45 min · 1,642 flights
- Mondays73% on time · p90 50 min · 2,050 flights
- Fridays73% on time · p90 60 min · 2,073 flights
- Thursdays73% on time · p90 50 min · 2,046 flights
- Sundays71% on time · p90 60 min · 2,022 flights
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