San Francisco (SFO) to Boston (BOS): On-Time Performance
Data through July 2026
When you fly SFO to BOS matters as much as anything else about the booking: the route swung from 92% on-time in April 2025 to just 67% in July 2026. Across the full period the route averages 78% on-time against a national 78%.
- On-time
- 78%
- arrived <15 min late
- Avg delay
- 16 min
- completed flights
- Cancelled
- 1.1%
- Flights/day
- 13
- last 12 months
- Duration
- 5h 44m
- scheduled
- Distance
- 2,704 mi
Best airline from SFO to BOS
4 airlines flew this route regularly between 2024-07 and 2026-07.
| Airline | On-time | Avg delay | Cancelled | Flights |
|---|---|---|---|---|
| United Airlinesmost reliable | 81% | 14 min | 0.8% | 3,816 |
| Alaska Airlines | 80% | 11 min | 0.2% | 618 |
| Delta Air Lines | 77% | 17 min | 1.3% | 1,835 |
| JetBlue Airways | 76% | 19 min | 1.4% | 3,492 |
Monthly on-time trend
Best time to fly from SFO to BOS
Aim for departures around 7 a.m. (89% on-time); avoid 11 a.m. departures (69%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Monday | 76% | 18 min |
| Tuesday | 82% | 15 min |
| Wednesday | 81% | 14 min |
| Thursday | 72% | 21 min |
| Friday | 77% | 15 min |
| Saturdaybest | 84% | 13 min |
| Sunday | 79% | 15 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft35%
- Airline operations26%
- National airspace system37%
- Weather2%
Frequently asked questions
- How often are flights from SFO to BOS delayed?
- 22% of SFO–BOS flights arrived 15 or more minutes late (the US DOT definition of a delay) between 2024-07 and 2026-07. The average arrival delay across completed flights was 16 minutes.
- Which airline is most reliable from SFO to BOS?
- United Airlines has the best on-time record on this route at 81%, based on 3,816 flights. 4 airlines flew SFO–BOS frequently enough to compare in this period.
- What is the best time of day to fly from SFO to BOS?
- Departures around 7 a.m. have the best record (89% on-time), while departures around 11 a.m. have the worst (69%). As on most US routes, delays accumulate through the day, so earlier flights are generally safer.
- How long is the flight from SFO to BOS?
- The scheduled SFO–BOS flight time averages 5h 44m over 2,704 miles. Actual arrival times vary — flights on this route land 15+ minutes late 22% of the time.
- How often are SFO to BOS flights cancelled?
- 1.1% of scheduled flights on this route were cancelled between 2024-07 and 2026-07, at or below the national rate of 1.6%.
- What is the worst month to fly from SFO to BOS?
- July 2026 was the roughest month in this dataset, with only 67% of arrivals on time. The best was April 2025 at 92%. If your dates are flexible, that 25-point gap is worth planning around.
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Based on 9,762 flights, 2024-07–2026-07. Source: US DOT Bureau of Transportation Statistics. Updated 2026-09-28.