Route reliability record
SMF→SEA
Sacramento to Seattle
- Flights
- 4,396
- Period
- September 2025 to August 2026
- Distance
- 605 mi
- Carriers
- 3
This route lands a B+, 6 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 roughly 45 minutes on average. That rests on 4,396 SMF to SEA flights, of which SkyWest Airlines flew 1,851 at 87.6% on time.
Best time to fly SMF to SEA: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 92.7% of the time and Tuesday flights 86.6%, against 83.0% for the route overall.
SkyWest Airlines is the most reliable of the three carriers covered here at 87.6% on time across 1,851 flights.
Key figures
On time
83.0%
Arrivals under 15 minutes late, of 4,379 completed flights
Avg delay
47 min
Across delayed arrivals only, not all flights
Cancelled
0.30%
National rate is 1.89%
Best carrier
SkyWest
87.6% on time across 1,851 flights
These figures cover 4,396 flights between September 2025 and August 2026. The median arrival is 8 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 SMF to SEA
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 87.6% of the time; Southwest Airlines manages 78.1%. Sample sizes sit next to every figure, because a two-point gap across 1,138 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 1,851 | 87.6% | 58 min | 0.27% | A+ |
| Alaska Airlines | 1,407 | 80.9% | 44 min | 0.43% | B+ |
| Southwest Airlines | 1,138 | 78.1% | 42 min | 0.18% | B+ |
SkyWest leads Southwest by 10 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Flights on SMF to SEA
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 Sacramento to Seattle
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. SMF → SEASacramento to Seattle | SkyWest Airlines | 87.4% | 87.6% | 0.27% | 11am–2pm, Tue | OO 4075 06:30 |
| 2. SMF → SEASacramento to Seattle | Alaska Airlines | 80.6% | 80.9% | 0.43% | 5am–8am, Tue | — |
| 3. SMF → SEASacramento to Seattle | Southwest Airlines | 78.0% | 78.1% | 0.18% | 5am–8am, Wed | — |
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 17 points, against 10 points between the best and worst carrier.
- 5am–8am942 flights92.7%
- 8am–11am555 flights77.9%
- 11am–2pm1,072 flights86.8%
- 2pm–5pm397 flights78.5%
- 5pm–8pm856 flights77.8%
- 8pm–5am574 flights75.6%
Scale runs 65% to 100%.
Book the early departure. Flights leaving between 5am–8am arrive on time 92.7% of the time, against 75.6% for the overnight window. That is 17 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 1,072 flights scheduled in it.
Explore
Filter SMF to SEA 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 SMF to SEA, the best departure window is 5am–8am at 92.7% on time and the worst is 8pm–5am at 75.6%, a wide gap of 17.1 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am92.7%
- 8–11am77.9%
- 11am–2pm86.8%
- 2–5pm78.5%
- 5–8pm77.8%
- 8pm–5am75.6%
best all US flightsScale 60% to 95%.
Across the year
When delays peak on this route
This route's year swings by 12 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.
June is the worst month at 77.9% on time, 12 points below February, the best at 90.1%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. August was the busiest month here, with 432 flights.
Across the week, Tuesday is the strongest day at 86.6% on time and Thursday the weakest at 79.6%, a spread of 7 points.
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 35,000 reported delay minutes.
- 39%Carrier
- 27%Late-arriving aircraft
- 25%National Airspace System
- 9%Extreme weather
- 0%Security
The largest share of delay minutes, 39%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 14,000 of the 35,000 delay minutes reported here. The split is drawn from 35,307 reported delay minutes.
Cancellations are rare at 0.30%, 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 3.6% 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 82.1% on time across 4,387 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 4,396 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 SEA 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. February runs 90.1% on time and June 77.9%, a swing of 12 points. If the dates move at all, move them out of June before you think about anything else. 4,379 completed flights over 12 months sit behind that.
Common questions
SMF to SEA questions
How often is SMF to SEA 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 17.0% of the 4,396 flights in this analysis, against 22.7% nationally. Delayed flights are late by roughly 45 minutes on average.
Which airline is most reliable on SMF to SEA?
SkyWest Airlines leads at 87.6% on time across 1,851 flights. Southwest Airlines is at the other end on 78.1%, a gap of 10 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 SMF to SEA?
The 5am–8am departure window is the strongest at 92.7% on time. The 8pm–5am window is the weakest at 75.6%, 17 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 June delays on SMF to SEA?
June is the weakest month at 77.9% on time, compared with 90.1% in February. Across the year that is 12 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
- SEA to SMF — the return legseparate record
- Sacramento International (SMF) delay statistics
- Seattle-Tacoma International (SEA) delay statistics
- SkyWest Airlines on SMF to SEA87.6%
- Alaska Airlines on SMF to SEA80.9%
- Southwest Airlines on SMF to SEA78.1%
- SMF to LAX, a related route85.6%
- LAX to SEA, a related route85.0%
- SMF to SAN, a related route69.8%
- SkyWest Airlines on-time record87.6%
- Alaska Airlines on-time record80.9%
- Southwest Airlines on-time record78.1%
- The best time of day to fly, according to 7.05 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. SMF to SEA and SEA to SMF 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.