Route reliability record
EWR→SFO
Newark to San Francisco
- Flights
- 4,416
- Period
- June 2025 to May 2026
- Distance
- 2,565 mi
- Carriers
- 2
This route sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 6 points worse than the national rate of 77.4%. The late ones land an hour and a half behind schedule. That rests on 4,416 flights, of which Alaska Airlines flew 663 at 75.3% on time.
The national on-time rate over the same period is 77.4%, so this route runs 6 points behind the country as a whole. Across a thousand flights that is about 62 extra late arrivals.
Key figures
On time
71.2%
Arrivals under 15 minutes late, of 4,293 completed flights
Avg delay
92 min
Across delayed arrivals only, not all flights
Cancelled
2.47%
National rate is 1.80%
Best carrier
Alaska
75.3% on time across 663 flights
These figures cover 4,416 flights between June 2025 and May 2026. Beyond the headline rate, 13.0% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
Which airline is most reliable on EWR to SFO
The two carriers here are closely matched: 5 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Alaska Airlines | 663 | 75.3% | 71 min | 1.36% | B |
| United Airlines | 3,753 | 70.5% | 95 min | 2.66% | C |
No carrier stands out. Alaska tops the table at 75.3%, 5 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 21 points, against 5 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am839 flights78.7%
- 8am–11am906 flights75.7%
- 11am–2pm584 flights74.3%
- 2pm–5pm880 flights72.2%
- 5pm–8pm895 flights61.1%
- 8pm–5am312 flights58.2%
Scale runs 50% to 85%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 58.2% on time, against 78.7% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in.
Across the year
When delays peak on this route
This route's year swings by 23 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
December is the weak month at 58.0% on time, against 81.2% in March. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days.
Across the week, Tuesday is the strongest day at 78.5% on time and Sunday the weakest at 67.2%. 11 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 114,000 reported delay minutes.
- 35%Carrier
- 33%Late-arriving aircraft
- 27%National Airspace System
- 5%Extreme weather
- 0%Security
The largest share of delay minutes, 35%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 39,000 of the 114,000 delay minutes reported here.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 78.7% on time here.
Cancellations sit at 2.47% against a national 1.80%, which is ordinary. Diversions add another 0.32%.
Connections and stage length
What a delay here actually costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 13.0% of arrivals land a full hour or more behind schedule, against 8.2% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
At 2,565 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg is a different operation and performs like one: it runs 75.9% on time across 4,414 flights, 5 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 5 points of difference.
The sample behind these figures is 4,416 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. March runs 81.2% on time and December 58.0%, a swing of 23 points. If the dates move at all, move them out of December before you think about anything else.
Common questions
EWR to SFO questions
How often is EWR to SFO delayed?
Roughly one flight in three arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 28.8% of the 4,416 flights in this analysis, against 22.6% nationally. Delayed flights are late by an hour and a half on average.
Which airline is most reliable on EWR to SFO?
Alaska Airlines leads at 75.3% on time across 663 flights. United Airlines is at the other end on 70.5%, a gap of 5 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on EWR to SFO?
The 5am–8am departure window is the strongest at 78.7% on time. The 8pm–5am window is the weakest at 58.2%, 21 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are December delays on EWR to SFO?
December is the weakest month at 58.0% on time, compared with 81.2% in March. Across the year that is 23 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- SFO to EWR — the return legseparate record
- Newark Liberty International (EWR) delay statistics
- San Francisco International (SFO) delay statistics
- Alaska Airlines on-time record75.3%
- United Airlines on-time record70.5%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Direction matters. EWR to SFO and SFO to EWR are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, June 2025 to May 2026. Updated monthly. How this data is collected.