Carrier route record

OOSEA→SFO

SkyWest Airlines · Seattle to San Francisco

Flights: 1,081
Period: July 2025 to June 2026
Share of route: 16%
Carriers: 5

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with SkyWest Airlines.

SkyWest on SEA to SFO sits in the middle of the pack with a B. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.6%. The late ones land roughly 55 minutes behind schedule. That rests on 1,081 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 923 at 67.3% on time.

The US average over the same twelve months is 77.6%, so there is little to separate SkyWest on SEA to SFO from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

75.4%

Arrivals under 15 minutes late, of 1,070 completed flights

Avg delay

53 min

Across delayed arrivals only, not all flights

Cancelled

1.02%

National rate is 1.81%

Whole route

65.6%

Every carrier on SEA to SFO, 6,764 flights

These figures cover 1,081 flights between July 2025 and June 2026. The median arrival is 3 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.

Carrier by carrier

SkyWest against every carrier on SEA to SFO

SkyWest flew 1,081 of the 6,764 flights on SEA to SFO, about 16% of it. Its 75.4% on time is 10 points better than the route as a whole, which runs 65.6%. Ranked by on-time rate it is number two of five carriers on the route, where the range runs from Southwest at 100.0% to Alaska at 60.3%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 67.3% of the time; Alaska Airlines manages 60.3%. Sample sizes sit next to every figure, because a two-point gap across 2,716 flights means less than a ten-point one.

On-time performance by carrier on SEA to SFO
Airline	Flights	On time	Avg delay	Cancelled	Grade
Southwest Airlinesthin sample	4	100.0%	—	0.00%	A+
SkyWest Airlines (this page)	1,081	75.4%	53 min	1.02%	B
Delta Air Lines	923	67.3%	56 min	1.63%	C
United Airlines	2,040	66.5%	71 min	0.83%	C+
Alaska Airlines	2,716	60.3%	52 min	1.40%	D

Delta leads Alaska by 7 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Flight by flight

SkyWest flight numbers on SEA to SFO

Departure window

When SkyWest runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 26 points, against 7 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am345 flights85.6%
8am–11am37 flights59.5%
11am–2pm272 flights78.4%
2pm–5pm196 flights66.0%
5pm–8pm228 flights67.8%
8pm–5am3 flights—

Scale runs 50% to 90%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 85.6% of the time, against 59.5% for the morning window. That is 26 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 345 flights scheduled in it.

Across the year

SkyWest on SEA to SFO through the year

Darker means more delays. Figures are on-time percentages.July best, June worst

June is the worst month at 49.0% on time, 41 points below July, the best at 89.9%. 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. March was the busiest month here, with 109 flights.

Across the week, Saturday is the strongest day at 81.9% on time and Friday the weakest at 72.0%. 10 points is a smaller lever than departure hour, but it is free.

Delay causes

Why SkyWest runs late on this route

One category carries most of the weight here. National Airspace System accounts for 46% of the 14,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.

National Airspace System
46%
Carrier
41%
Extreme weather
12%
Late-arriving aircraft
1%
Security
0%

Extreme weather accounts for 12% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 2.0 times the usual weather exposure. The split is drawn from 13,875 reported delay minutes.

The largest share of delay minutes, 41%, 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 5,693 of the 14,000 delay minutes reported here.

Cancellations sit at 1.02% against a national 1.81%, which is ordinary. Diversions add another 0.00%.

Connections and stage length

What a delay here costs

6.6% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last roughly 55 minutes, which a normal layover absorbs.

The 679 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. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

The return leg runs 72.7% on time across 1,082 flights, within 3 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

One caution: this is a thin sample. 1,081 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.

What to do with this

Booking SkyWest on SEA to SFO

Put together: treat all of this as provisional. 1,081 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 75.4% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,070 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures