BOS → SFO Flight Reliability

Right now

Origin · BOSNo disruption reported

Aviation weather is not currently a factor.

Updated 09:54 UTC

Boston airport profile →

Destination · SFONo disruption reported

Aviation weather is not currently a factor.

Updated 09:56 UTC

San Francisco airport profile →

Route reliability

July 2023 – July 2026

Route Reliability Score

61/ 100Good

Better than 37% of comparable major US routes (4,598 compared)

Calculated from 14,232 flights. How this is calculated

On-time arrivals

74.6%

10,472 of 14,043

Cancellation rate

1.03%

147 cancelled

Median arrival delay

-6 min

Average 5.0 min

Severe delays

8.8%

60+ minutes late

Delay when late

64 min

Average, when 15+ min late

Flights analyzed

14,232

4 carriers

BOS → SFO arrives on time 74.6% of the time; the return trip, SFO → BOS, arrives on time 77.9% of the time, a 3.3-point gap between the two directions of the same city pair.

BOS → SFO spends 30.7 minutes on the ground on a 2,704-mile trip: 22.0 minutes from pushback to wheels-up at BOS and 8.7 minutes from touchdown to gate at SFO.

Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026

Why BOS → SFO flights are cancelled

July 2023 – July 2026

BOS → SFO cancelled 147 of 14,232 scheduled flights — about 1 in every 97. The reason filed most often was the airline, 51.0% of the cancellations coded on this route — about 1 in every 190 scheduled flights.

Share of cancellations

Airline51.0%

Weather34.7%

Air traffic14.3%

Security0.0%

Of 147 cancelled departures carrying a reason code.

What each reason means

The airline1 in 190

Crew, maintenance, aircraft cleaning, baggage or fueling: what BTS counts as within the carrier’s own control.

75 cancellations, 51.0% of the total.

Extreme weather1 in 279

Conditions the carrier judged severe enough to stop the flight: a blizzard, a hurricane, a line of thunderstorms.

51 cancellations, 34.7% of the total.

The air traffic system1 in 678

Airport capacity, air traffic control flow programs, heavy traffic and ordinary bad weather. A system decision, not the airline’s.

21 cancellations, 14.3% of the total.

Security—

A terminal evacuation, a security breach, screening equipment failure, or screening queues over 29 minutes.

0 cancellations, 0.0% of the total.

Reason codes are the operating airline’s own filing with US DOT, not an independent finding of fault. Ordinary bad weather is filed under air traffic, so weather’s full share is larger than its bar.

147 coded cancellations were recorded on BOS → SFO; the section appears from 50.

When it goes wrong

July 2023 – July 2026

One arrival in ten is worse than

54 min late

against a median of 6 min early

Arrived an hour or more late8.8%

Typical delay when late64 min

Cancelled1.03%

Landed somewhere else0.30%

Percentiles over 14,232 operations; cancelled and diverted flights are counted separately.

Will your connection be tight enough?

Layovers at SFO after arriving from BOS.

Connection buffer and chance of missing by layover length, BOS → SFO arrivals
Connection time	Chance of missing	Reads as
30 min	40%	Likely to miss
45 min	25%	High risk
60 min	16%	High risk
90 min	8.6%	Some risk
120 min	5.0%	Some risk

This is one leg of a connection. Gate changes and the next flight's own schedule matter too. And a connection can fail before delay is even the question — this route cancels 1.03% of the time and diverts 0.30% of the time, which a late arrival never shows up in.

Chance of missing is the share of 14,043 arrivals on this route that landed later than the connection time less 30 minutes to reach the next gate.

The worst tenth of arrivals on this route land at least 54 minutes late (90th-percentile gate arrival delay), over 14,232 operations.

Any other layover length: connection checker.

Best time to fly

BOS → SFO flights departing 5–9 AM arrived on time 83.7% of the time, against 58.0% for 9 PM–5 AM departures, a gap of 25.7 percentage points.

By day and hour

On-time arrival rate for each weekday and scheduled departure hour, in local time at the departure airport (BOS).

Hour of departure matters more than day of the week: hourly averages sit a typical 9.4 points from the route-wide rate, weekday averages 3.1 points.

On-time arrival rate for BOS to SFO by weekday and scheduled departure hour, local time. Each button reads out one slot.
Hour	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday	Sunday
6 AM–7 AM
7 AM–8 AM
8 AM–9 AM
9 AM–10 AM
10 AM–11 AM
11 AM–12 PM
12 PM–1 PM
1 PM–2 PM
2 PM–3 PM
3 PM–4 PM
4 PM–5 PM
5 PM–6 PM
6 PM–7 PM
7 PM–8 PM
8 PM–9 PM

On-time rate, % · stronger color, fewer on time

50–59
60–69
70–79
80–89

Fewer than 120 flights, not scored

Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · On time is arrival within 15 minutes of schedule. Cells round to whole percentages; the table shows one decimal.

No slot is named best or worst: too few reach 500 flights. Departures before 6 AM and after 9 PM (515 flights) are not drawn: no slot in those hours has enough flights to score.

View as tableHide table

On-time arrival rate (%) with flights beneath, by scheduled departure hour and weekday for BOS to SFO. A dash means fewer than 120 flights, which are not scored.
Hour	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday	Sunday
6 AM–7 AM	85.5% on time222 flights	86.7% on time206 flights	87.5% on time205 flights	86.1% on time218 flights	87.8% on time224 flights	83.7% on time173 flights	86.8% on time206 flights
7 AM–8 AM	82.7% on time302 flights	83.6% on time288 flights	82.7% on time284 flights	81.6% on time302 flights	78.7% on time306 flights	74.9% on time232 flights	82.2% on time291 flights
8 AM–9 AM	81.0% on time192 flights	89.3% on time189 flights	85.7% on time184 flights	88.8% on time190 flights	81.8% on time188 flights	82.6% on time169 flights	84.3% on time187 flights
9 AM–10 AM	91 flights, too few to score	99 flights, too few to score	91 flights, too few to score	92 flights, too few to score	94 flights, too few to score	36 flights, too few to score	95 flights, too few to score
10 AM–11 AM	109 flights, too few to score	110 flights, too few to score	113 flights, too few to score	112 flights, too few to score	116 flights, too few to score	88 flights, too few to score	105 flights, too few to score
11 AM–12 PM	111 flights, too few to score	102 flights, too few to score	102 flights, too few to score	110 flights, too few to score	110 flights, too few to score	92 flights, too few to score	114 flights, too few to score
12 PM–1 PM	10 flights, too few to score	8 flights, too few to score	10 flights, too few to score	10 flights, too few to score	14 flights, too few to score	8 flights, too few to score	10 flights, too few to score
1 PM–2 PM	80.8% on time132 flights	85.0% on time127 flights	85.2% on time128 flights	80.6% on time129 flights	75.0% on time131 flights	113 flights, too few to score	74.0% on time133 flights
2 PM–3 PM	26 flights, too few to score	26 flights, too few to score	27 flights, too few to score	26 flights, too few to score	26 flights, too few to score	35 flights, too few to score	25 flights, too few to score
3 PM–4 PM	67 flights, too few to score	67 flights, too few to score	65 flights, too few to score	67 flights, too few to score	68 flights, too few to score	44 flights, too few to score	68 flights, too few to score
4 PM–5 PM	63.2% on time121 flights	74 flights, too few to score	76 flights, too few to score	56.3% on time120 flights	59.5% on time122 flights	41 flights, too few to score	111 flights, too few to score
5 PM–6 PM	69.5% on time193 flights	71.6% on time209 flights	73.5% on time205 flights	63.7% on time191 flights	66.5% on time193 flights	70.3% on time183 flights	60.0% on time200 flights
6 PM–7 PM	61.2% on time242 flights	72.9% on time243 flights	68.6% on time245 flights	55.8% on time236 flights	61.7% on time239 flights	71.4% on time232 flights	56.4% on time237 flights
7 PM–8 PM	61 flights, too few to score	56 flights, too few to score	57 flights, too few to score	59 flights, too few to score	58 flights, too few to score	74 flights, too few to score	58 flights, too few to score
8 PM–9 PM	62.4% on time191 flights	114 flights, too few to score	67.7% on time134 flights	50.5% on time191 flights	67.7% on time192 flights	67.7% on time126 flights	54.0% on time183 flights

By departure window

5–9 AM83.7%

9 AM–12 PM79.3%

12–3 PM80.7%

3–6 PM67.3%

6–9 PM62.9%

9 PM–5 AM58.0%

By departure hour

12 AM

3 AM

6 AM

9 AM

12 PM

3 PM

6 PM

9 PM

Why BOS → SFO runs late

July 2023 – July 2026

Air traffic control33.9%

airspace and airport capacity, including weather-driven flow control

Late-arriving aircraft32.6%

the inbound aircraft was late, so this flight started late

The airline30.3%

crew, maintenance, boarding and fueling, all within the carrier’s control

Weather3.1%

weather severe enough to stop this flight specifically

Security0.1%

screening or terminal security incidents

Share of the delay minutes US DOT attributed to each cause for BOS → SFO. Only delays of 15 minutes or more are attributed.

How this route holds up in bad weather

July 2023 – July 2026

The harder-hit end is the one the flight leaves from, where a cancellation keeps it from departing at all. Bad weather cancels 3.9 times the normal rate at BOS against 1.7 times at SFO. Cancelled in bad weather against normal hours: BOS 5.3% against 1.4%, SFO 1.5% against 0.9%. Flights that did leave BOS in bad weather arrived on time 65.1% of the time, against 79.7% in normal hours.

Bad weather and normal hours at the airports

Scheduled departures, July 2023 – July 2026

Departures from BOS and SFO in hours of bad weather and in normal hours
Departures from	BOS	SFO
Cancelled in bad weather	5.3%	1.5%
Cancelled in normal hours	1.4%	0.9%
Arrived on time, bad weather	65.1%	73.0%
Arrived on time, normal hours	79.7%	79.8%
Departures in bad weather	60,840	36,006

Delta Air Lines (3.1% cancelled against 5.8% for the other carriers at BOS), Alaska Airlines (2.9% cancelled against 5.0% for the other carriers at BOS) and United Airlines (4.6% cancelled against 5.4% for the other carriers at BOS) cancelled fewer departures from BOS in bad weather than the other carriers there did in the same months. None of the route’s other carriers was clearly worse.

This route’s airlines in bad weather at BOS

All departures from BOS

Cancellation rates in bad weather at BOS for the airlines that fly BOS to SFO, against the other carriers at BOS in the same months
Airline	Bad-weather departures	Cancelled	Other carriers
Delta Air Lines	10,971	3.1%below the others	5.8%
Alaska Airlines	1,021	2.9%below the others	5.0%
United Airlines	5,328	4.6%below the others	5.4%
JetBlue	17,332	5.4%about level	5.1%

These are airport figures, not route figures: every scheduled departure from BOS and SFO, to any destination, in hours the weather report called bad. The airline rows count each carrier’s departures from BOS on every route.

Weather source and limits. In full: BOS (airlines), SFO, What Weather Costs Each Airport, Who Cancels More When the Weather Turns, Airports That Change Places When Weather Turns.

Airlines on this route

Carriers with at least 200 flights, by the airline that operated each one.

Airlines on this route
Carrier	Flights	On time	Cancelled	Median delay	Severe
United Airlines	5,526	78.7%	1.19%	-8 min	7.7%
JetBlue	5,059	71.8%	0.89%	-5 min	10.3%
Delta Air Lines	2,529	73.6%	0.91%	-6 min	7.8%
Alaska Airlines	1,117	69.2%	1.16%	-3 min	10.1%

United Airlines flew 38.8% of the 14,231 flights listed.

United Airlines arrived on time 9.5 percentage points more often than Alaska Airlines on this route.

Flights on this route

Flight numbers with at least 600 operations here and still on the schedule.

Flights on this route
Flight	Scheduled	Operations	On time
UA2400 United Airlines	6:18 PM	1,033	62.0%
B6333 JetBlue	8:59 PM	1,021	60.5%
DL977 Delta Air Lines	7:55 AM	893	80.8%
B6733 JetBlue	6:30 PM	794	68.2%
B61833 JetBlue	9:50 AM	712	79.3%
B61333 JetBlue	6:05 AM	601	84.3%

B61333 (6:05 AM) arrived on time 84.3% of the time, 23.8 points more often than B6333 (8:59 PM) at 60.5%.

Weekly and seasonal patterns

By day of week

Mon73.4%

Tue79.8%

Wed78.3%

Thu71.5%

Fri72.3%

Sat75.8%

Sun71.6%

Tuesday is historically the most reliable day and Thursday the least, a gap of 8.3 percentage points.

By month

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

June is historically the weakest month and September the strongest, a spread of 13.4 percentage points.

Reliability over time

July 2023 – July 2026

24

25

26

Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 71.5% against 78.8% in the 12 months before — declining by 7.3 percentage points.

Data and methodology

Calculated by FlyerIntel from 14,232 BOS → SFO flight records from the US DOT Bureau of Transportation Statistics, covering July 2023 – July 2026. Late means 15 or more minutes past scheduled arrival; cancelled and diverted flights are left out of on-time rates.

Full methodology · Data sources · Report a problem

Analysis last recomputed September 26, 2026

BOS airport SFO airport Return direction SFO → BOS

BOS→SFO

Right now

Route reliability

Why BOS → SFO flights are cancelled

Share of cancellations

What each reason means

When it goes wrong

Will your connection be tight enough?

Best time to fly

By day and hour

By departure window

By departure hour

Why BOS → SFO runs late

How this route holds up in bad weather

Bad weather and normal hours at the airports

This route’s airlines in bad weather at BOS

Airlines on this route

Flights on this route

Weekly and seasonal patterns

By day of week

By month

Reliability over time

Data and methodology