Route reliability record
SEA→SMF
Seattle to Sacramento
- Flights
- 4,387
- Period
- September 2025 to August 2026
- Distance
- 605 mi
- Carriers
- 3
This route lands a B+, 5 points better than the national rate of 77.3%. About one flight in six arrives 15 minutes late or worse, and those flights are late by about 50 minutes on average. That rests on 4,387 SEA to SMF flights, of which SkyWest Airlines flew 1,839 at 89.1% on time.
Best time to fly SEA to SMF: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 93.5% of the time and Tuesday flights 87.0%, against 82.1% for the route overall.
SkyWest Airlines is the most reliable of the three carriers covered here at 89.1% on time across 1,839 flights.
Key figures
On time
82.1%
Arrivals under 15 minutes late, of 4,360 completed flights
Avg delay
51 min
Across delayed arrivals only, not all flights
Cancelled
0.39%
National rate is 1.89%
Best carrier
SkyWest
89.1% on time across 1,839 flights
These figures cover 4,387 flights between September 2025 and August 2026. The median arrival is 6 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
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Carrier by carrier
Which airline is most reliable on SEA to SMF
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 89.1% of the time; Southwest Airlines manages 73.3%. Sample sizes sit next to every figure, because a two-point gap across 1,139 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 1,839 | 89.1% | 63 min | 0.27% | A+ |
| Alaska Airlines | 1,409 | 80.2% | 44 min | 0.57% | B+ |
| Southwest Airlines | 1,139 | 73.3% | 48 min | 0.35% | C+ |
The spread between SkyWest and Southwest is 16 points, wide enough that it should decide the booking. On a hundred trips that is 16 more arrivals inside the on-time window.
Flight by flight
Flights on SEA to SMF
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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Best ways to make this trip
The most reliable ways to fly Seattle to Sacramento
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. SEA → SMFSeattle to Sacramento | SkyWest Airlines | 88.9% | 89.1% | 0.27% | 8am–11am, Tue | OO 3881 08:25 |
| 2. SEA → SMFSeattle to Sacramento | Alaska Airlines | 79.7% | 80.2% | 0.57% | 5am–8am, Tue | AS 681 14:16 |
| 3. SEA → SMFSeattle to Sacramento | Southwest Airlines | 73.0% | 73.3% | 0.35% | 5am–8am, Tue | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
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 16 points between the best and worst carrier.
- 5am–8am543 flights93.5%
- 8am–11am1,023 flights87.9%
- 11am–2pm588 flights77.6%
- 2pm–5pm762 flights82.1%
- 5pm–8pm626 flights72.6%
- 8pm–5am845 flights78.1%
Scale runs 65% to 100%.
Book the early departure. Flights leaving between 5am–8am arrive on time 93.5% of the time, against 72.6% for the evening window. That is 21 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 1,023 flights scheduled in it.
Explore
Filter SEA to SMF by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On SEA to SMF, the best departure window is 5am–8am at 93.5% on time and the worst is 5pm–8pm at 72.6%, a wide gap of 20.9 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am93.5%
- 8–11am87.9%
- 11am–2pm77.6%
- 2–5pm82.1%
- 5–8pm72.6%
- 8pm–5am78.1%
best all US flightsScale 60% to 100%.
Across the year
When delays peak on this route
This route's year swings by 14 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 73.4% on time, against 87.5% in April. 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. August was the busiest month here, with 433 flights.
Across the week, Tuesday is the strongest day at 87.0% on time and Thursday the weakest at 78.4%, a spread of 9 points.
Delay causes
Why this route gets delayed
Carrier accounts for 42% of the 39,000 delay minutes carriers reported here, and the remaining four split what is left.
- 42%Carrier
- 40%Late-arriving aircraft
- 9%Extreme weather
- 9%National Airspace System
- 0%Security
40% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 39,000 reported delay minutes here, that single category outweighs weather by 5 to one. The split is drawn from 39,323 reported delay minutes.
The largest share of delay minutes, 42%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 17,000 of the 39,000 delay minutes reported here.
Cancellations are rare at 0.39%, below the national 1.89% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here actually costs
Badly late arrivals are rare here: only 4.2% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
The 605 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.
The return leg runs 83.0% on time across 4,396 flights, within about a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 4,387 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.
Work out the risk of missing a connection in SMF after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. April runs 87.5% on time and December 73.4%, a swing of 14 points. If the dates move at all, move them out of December before you think about anything else. 4,360 completed flights over 12 months sit behind that.
Common questions
SEA to SMF questions
How often is SEA to SMF delayed?
About one flight in six arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 17.9% of the 4,387 flights in this analysis, against 22.7% nationally. Delayed flights are late by about 50 minutes on average.
Which airline is most reliable on SEA to SMF?
SkyWest Airlines leads at 89.1% on time across 1,839 flights. Southwest Airlines is at the other end on 73.3%, a gap of 16 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 SEA to SMF?
The 5am–8am departure window is the strongest at 93.5% on time. The 5pm–8pm window is the weakest at 72.6%, 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 SEA to SMF?
December is the weakest month at 73.4% on time, compared with 87.5% in April. Across the year that is 14 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
- SMF to SEA — the return legseparate record
- Seattle-Tacoma International (SEA) delay statistics
- Sacramento International (SMF) delay statistics
- SkyWest Airlines on SEA to SMF89.1%
- Alaska Airlines on SEA to SMF80.2%
- Southwest Airlines on SEA to SMF73.3%
- SEA to LAX, a related route82.0%
- LAX to SMF, a related route84.8%
- SEA to PHX, a related route78.2%
- SkyWest Airlines on-time record89.1%
- Alaska Airlines on-time record80.2%
- Southwest Airlines on-time record73.3%
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
Direction matters. SEA to SMF and SMF to SEA are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.