Route reliability record
SEA→JNU
Seattle to Juneau
- Flights
- 1,588
- Period
- September 2025 to August 2026
- Distance
- 909 mi
- Carriers
- 2
This route lands a B, 2 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about 50 minutes on average. That rests on 1,588 SEA to JNU flights, with a median arrival 5 minutes early.
Best time to fly SEA to JNU: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 87.1% of the time and Wednesday flights 84.5%, against 79.2% for the route overall.
The US average over the same twelve months is 77.3%, 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
79.2%
Arrivals under 15 minutes late, of 1,561 completed flights
Avg delay
51 min
Across delayed arrivals only, not all flights
Cancelled
1.26%
National rate is 1.89%
Best carrier
Alaska
78.7% on time across 1,447 flights
These figures cover 1,588 flights between September 2025 and August 2026. The median arrival is 5 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 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 | 84.9% | 42 min | 1.42% | B |
| Alaska Airlines | 1,447 | 78.7% | 51 min | 1.24% | 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.
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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 12 points, against half a point between the best and worst carrier.
- 5am–8am362 flights87.1%
- 8am–11am144 flights76.8%
- 11am–2pm455 flights76.9%
- 2pm–5pm141 flights84.9%
- 5pm–8pm9 flights—
- 8pm–5am477 flights74.8%
Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 87.1% of the time, against 74.8% for the overnight window. That is 12 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8pm–5am window is the busiest, with 477 flights scheduled in it.
Explore
Filter SEA to JNU 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 JNU, the best departure window is 5am–8am at 87.1% on time and the worst is 8pm–5am at 74.8%, a wide gap of 12.3 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am87.1%
- 8–11am76.8%
- 11am–2pm76.9%
- 2–5pm84.9%
- 5–8pm—
- 8pm–5am74.8%
best all US flightsScale 60% to 95%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 27 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 65.1% on time, against 92.0% 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. July was the busiest month here, with 216 flights.
Across the week, Wednesday is the strongest day at 84.5% on time and Thursday the weakest at 71.2%, a spread of 13 points.
Delay causes
Why this route gets delayed
Carrier accounts for 52% of the 16,000 delay minutes carriers reported here, and the remaining four split what is left.
- 52%Carrier
- 30%Late-arriving aircraft
- 11%National Airspace System
- 7%Extreme weather
The largest share of delay minutes, 52%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 8,576 of the 16,000 delay minutes reported here. The split is drawn from 16,416 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 87.1% on time here.
Cancellations sit at 1.26% against a national 1.89%, 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 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about 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.
The return leg runs 81.4% on time across 1,589 flights, within 2 points 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 1,588 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 December 65.1%, a swing of 27 points. If the dates move at all, move them out of December before you think about anything else. 1,561 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 five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 20.8% of the 1,588 flights in this analysis, against 22.7% nationally. Delayed flights are late by about 50 minutes on average.
How reliable is SEA to JNU compared with the rest of the country?
79.2% of flights arrive on time here against a national 77.3%, a difference of 2 points in its favour. 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 87.1% on time. The 8pm–5am window is the weakest at 74.8%, 12 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 JNU?
December is the weakest month at 65.1% on time, compared with 92.0% in April. Across the year that is 27 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 JNU84.9%
- Alaska Airlines on SEA to JNU78.7%
- SEA to LAX, a related route82.0%
- ANC to JNU, a related route87.4%
- SEA to PHX, a related route78.2%
- Delta Air Lines on-time record84.9%
- Alaska Airlines on-time record78.7%
- 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. 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.