Route reliability record
PDX→BOI
Portland to Boise
- Flights
- 908
- Period
- July 2025 to June 2026
- Distance
- 344 mi
- Carriers
- 2
This route earns an A+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 9 points better than the national rate of 77.6%. When something does go wrong the average delay runs roughly 50 minutes. That rests on 908 PDX to BOI flights, with a median arrival 5 minutes early.
Best time to fly PDX to BOI: a 11am–2pm departure, ideally on a Tuesday. Flights in that window arrived on time 91.2% of the time and Tuesday flights 92.1%, against 86.7% for the route overall.
Set against the rest of the country, this route's record is 9 points better than the US average of 77.6%. That gap is worth roughly 91 fewer late arrivals for every thousand flights.
Key figures
On time
86.7%
Arrivals under 15 minutes late, of 901 completed flights
Avg delay
48 min
Across delayed arrivals only, not all flights
Cancelled
0.77%
National rate is 1.81%
Best carrier
Alaska
85.7% on time across 659 flights
These figures cover 908 flights between July 2025 and June 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.
Carrier by carrier
Which airline is most reliable on PDX to BOI
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 |
|---|---|---|---|---|---|
| SkyWest Airlinesthin sample | 249 | 89.3% | 63 min | 2.01% | A |
| Alaska Airlines | 659 | 85.7% | 44 min | 0.30% | A+ |
Departure window
The best time of day to leave
Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 908 flights.
- 5am–8am—
- 8am–11am214 flights89.0%
- 11am–2pm34 flights91.2%
- 2pm–5pm326 flights86.5%
- 5pm–8pm38 flights84.2%
- 8pm–5am296 flights85.0%
Scale runs 75% to 95%. Rows with fewer than 30 flights show a dash.
The best window here is not the first bank but the 11am–2pm slot at 91.2% on time, ahead of 5pm–8pm at 84.2%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 2pm–5pm window is the busiest, with 326 flights scheduled in it.
Across the year
When delays peak on this route
Twelve months, one bar each, drawn from the same 908 flights. The strip shows how much of this route's record is set by the calendar rather than by the operation.
December is the weak month at 81.3% on time, against 91.2% 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. January was the busiest month here, with 97 flights.
Across the week, Tuesday is the strongest day at 92.1% on time and Wednesday the weakest at 82.0%. 10 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. Late-arriving aircraft accounts for 57% of the 5,728 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.
- 57%Late-arriving aircraft
- 28%Carrier
- 14%National Airspace System
- 0%Extreme weather
57% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 5,728 reported delay minutes here, that single category outweighs weather by 57 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 5,728 reported delay minutes.
Cancellations are rare at 0.77%, below the national 1.81% 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 3.2% land an hour or more behind schedule, against 8.1% 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.
At 344 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 11am–2pm window matters as much as it does.
The return leg is a different operation and performs like one: it runs 91.9% on time across 1,115 flights, 5 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 5 points of difference.
One caution: this is a thin sample. 908 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.
Work out the risk of missing a connection in BOI after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 908 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 86.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 901 completed flights over 12 months sit behind that.
Common questions
PDX to BOI questions
How often is PDX to BOI delayed?
About one flight in eight arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 13.3% of the 908 flights in this analysis, against 22.4% nationally. Delayed flights are late by roughly 50 minutes on average.
How reliable is PDX to BOI compared with the rest of the country?
86.7% of flights arrive on time here against a national 77.6%, a difference of 9 points in its favour. That is worth a A+ on this site's grading scale.
What time of day has the fewest delays on PDX to BOI?
The 11am–2pm departure window is the strongest at 91.2% on time. The 5pm–8pm window is the weakest at 84.2%, 7 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 PDX to BOI?
December is the weakest month at 81.3% on time, compared with 91.2% in April. Across the year that is 10 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
- BOI to PDX — the return legseparate record
- Portland International (PDX) delay statistics
- SkyWest Airlines on PDX to BOI89.3%
- Alaska Airlines on PDX to BOI85.7%
- PDX to SEA, a related route84.8%
- SEA to BOI, a related route85.8%
- PDX to LAX, a related route87.4%
- SkyWest Airlines on-time record89.3%
- Alaska Airlines on-time record85.7%
- Why the first flight of the morning is statistically safest
- Worst months to fly in the US, ranked by the data
Direction matters. PDX to BOI and BOI to PDX are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Embed PDX to BOI’s on-time badge on your site
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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.