Route reliability record
SEA→JNU
Seattle to Juneau
- Flights
- 1,589
- Period
- July 2025 to June 2026
- Distance
- 909 mi
- Carriers
- 2
This route lands a B, about a point worse than the national rate of 77.6%. About one flight in four arrives 15 minutes late or worse, and those flights are late by roughly 50 minutes on average. That is a workable record, not a spotless one. That rests on 1,589 SEA to JNU flights, with a median arrival 3 minutes early.
Best time to fly SEA to JNU: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 83.2% of the time and Tuesday flights 80.7%, against 76.6% for the route overall.
The US average over the same twelve months is 77.6%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
76.6%
Arrivals under 15 minutes late, of 1,560 completed flights
Avg delay
48 min
Across delayed arrivals only, not all flights
Cancelled
1.38%
National rate is 1.81%
Best carrier
Alaska
76.3% on time across 1,448 flights
These figures cover 1,589 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
Which airline is most reliable on SEA to JNU
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Linesthin sample | 141 | 80.0% | 43 min | 0.71% | B+ |
| Alaska Airlines | 1,448 | 76.3% | 48 min | 1.45% | B |
Flight by flight
Flights on SEA to JNU
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.
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 40 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am362 flights83.2%
- 8am–11am144 flights78.2%
- 11am–2pm455 flights76.9%
- 2pm–5pm141 flights80.0%
- 5pm–8pm59 flights43.1%
- 8pm–5am428 flights73.6%
Scale runs 35% to 90%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 43.1% on time, against 83.2% 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. The 11am–2pm window is the busiest, with 455 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 31 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.
July is the worst month at 60.6% on time, 31 points below April, the best at 92.0%. 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. July was the busiest month here, with 217 flights.
Across the week, Tuesday is the strongest day at 80.7% on time and Thursday the weakest at 70.1%. 11 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Carrier accounts for 46% of the 17,000 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.
- 46%Carrier
- 33%Late-arriving aircraft
- 15%National Airspace System
- 5%Extreme weather
- 0%Security
The largest share of delay minutes, 46%, 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 8,032 of the 17,000 delay minutes reported here. The split is drawn from 17,397 reported delay minutes.
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 83.2% on time here.
Cancellations sit at 1.38% against a national 1.81%, which is ordinary. Diversions add another 0.44%.
Connections and stage length
What a delay here actually costs
5.1% 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 50 minutes, which a normal layover absorbs.
The 909 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 is a different operation and performs like one: it runs 80.3% on time across 1,591 flights, 4 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 4 points of difference.
The sample behind these figures is 1,589 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 JNU 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 92.0% on time and July 60.6%, a swing of 31 points. If the dates move at all, move them out of July before you think about anything else. 1,560 completed flights over 12 months sit behind that.
Common questions
SEA to JNU questions
How often is SEA to JNU delayed?
About one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 23.4% of the 1,589 flights in this analysis, against 22.4% nationally. Delayed flights are late by roughly 50 minutes on average.
How reliable is SEA to JNU compared with the rest of the country?
76.6% of flights arrive on time here against a national 77.6%, a difference of about a point against it. That is worth a B on this site's grading scale.
What time of day has the fewest delays on SEA to JNU?
The 5am–8am departure window is the strongest at 83.2% on time. The 5pm–8pm window is the weakest at 43.1%, 40 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 July delays on SEA to JNU?
July is the weakest month at 60.6% on time, compared with 92.0% in April. Across the year that is 31 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
- JNU to SEA — the return legseparate record
- Seattle-Tacoma International (SEA) delay statistics
- Delta Air Lines on SEA to JNU80.0%
- Alaska Airlines on SEA to JNU76.3%
- SEA to LAX, a related route83.4%
- ANC to JNU, a related route86.5%
- SEA to PHX, a related route79.2%
- Delta Air Lines on-time record80.0%
- Alaska Airlines on-time record76.3%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. SEA to JNU and JNU 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.