Historical on-time performance
San Francisco to Boston
Flights on SFO–BOS arrive on time 77% of the time over the last 12 months.
based on 4,577 flights over the last 12 months. On-time means arriving within 15 minutes (BTS standard).
By airline
How each carrier compares
Too close to call — no single carrier is clearly more on-time here.
- United AirlinesOn-time78%Medianon timep9050 minCancel1.0%Flights1,815
- JetBlue AirwaysOn-time77%Medianon timep9055 minCancel1.7%Flights1,617
- Delta Air LinesOn-time77%Medianon timep9045 minCancel1.4%Flights883
- Alaska AirlinesOn-time76%Medianon timep9040 minCancel0.4%Flights262
Why flights run late
Delay causes
- Airline22%
- Weather3%
- Air traffic (NAS)39%
- Late aircraft36%
- Security0%
Most delay minutes here are attributed to Air traffic (NAS).
When flights don't go
Why flights were cancelled
- Airline19%
- Weather71%
- Air traffic (NAS)10%
- Security0%
Most cancellations here are attributed to Weather. Shares are among 59 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 SFO → BOS
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 — 84% on time.
- Mornings84% on time · p90 25 min · 3,953 flights
- Afternoons78% on time · p90 45 min · 1,610 flights
- Overnights77% on time · p90 45 min · 3,842 flights
- Middays71% on time · p90 65 min · 4,238 flights
Best day of week
On-time rates are fairly even by day on this route — ranging from 73% to 82% on time.
- Tuesdays82% on time · p90 35 min · 1,898 flights
- Saturdays81% on time · p90 30 min · 1,603 flights
- Wednesdays80% on time · p90 35 min · 1,927 flights
- Fridays75% on time · p90 55 min · 2,074 flights
- Mondays75% on time · p90 50 min · 2,037 flights
- Sundays74% on time · p90 50 min · 2,048 flights
- Thursdays73% on time · p90 60 min · 2,057 flights
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