82% of flights leaving Boise (BOI) arrived on time over the past 12 months, 6 points better than the national average of 76%. That ranks 7 of 76 large U.S. airports. About 80 flights leave BOI on a typical day; 0.6% were cancelled. 83% pushed back from the gate on time, so most of the lateness is already there when the flight leaves the gate.
At a glance
- Best hour to fly: 6 a.m. (93% on time). Worst: 7 p.m. (70%).
- Best month: October (87%). Worst: July (80%).
- Most reliable airline here: Delta Air Lines (88%), vs United Airlines at 78%.
- Biggest delay cause: late-arriving aircraft (35% of delay minutes).
- Year on year: getting worse (84% → 82%).
How late?
The on-time rate treats a flight 20 minutes late the same as one 5 hours late. Here's the split for flights leaving BOI: when a flight was late, it was under 45 minutes late 58% of the time. About 1 in 19 flights landed an hour or more late, and 1 in 93 three hours or more; 0.6% were cancelled outright.
- On time or early82%
- 15–30 min late6.7%
- 30–60 min late5.0%
- 1–2 hours late3.3%
- 2–3 hours late1.0%
- 3+ hours late1.1%
- Diverted0.2%
- Cancelled0.6%
Share of all 29,120 scheduled flights, past 12 months, by arrival time against schedule.
Best time of day to fly out of BOI
Time of day matters more at BOI than almost anything else you control. Flights scheduled to leave at 6 a.m. arrived on time 93% of the time; at 7 p.m. it was 70%, a 23-point gap. Taken together, early departures (5–9 a.m.) ran 91% on time against 72% for the evening bank (5–10 p.m.). Early planes usually start the day at the airport, so they haven't had a chance to pick up delays elsewhere. By evening a late inbound aircraft, a crew running out of duty hours or an afternoon thunderstorm can push one late flight into the next. Cancellations cluster too: 8 p.m. departures were cancelled 1.1% of the time, against 0.6% overall.
Hour × month
Combine the two and the spread is wider still. The most reliable combination at BOI was a 5 a.m. departure in May (97% on time); the least, 8 p.m. in July (58%). If you can only move one thing, move the hour. Departure hour usually shifts the odds more than the month does.
Each cell: on-time rate for that departure hour in that calendar month, 2023–2026. Find your travel month, then look along the row for the greenest hour.
Best and worst months
July is the hardest month at BOI, with 80% of flights on time across 2023–2026; October is the best at 87%. Summer (June–August) runs 6 points worse than autumn: heavy schedules, peak loads and afternoon thunderstorms. Winter costs 4 points against autumn. Cancellations peak in January (1.0% of flights).
Airlines at BOI
Alaska Airlines runs 37% of departures from BOI. Among airlines with at least 1,000 departures here, Delta Air Lines was the most reliable (88% on time) and United Airlines the least (78%), a 10-point difference. On a route where both fly, that difference is worth more than a small fare gap.
| Airline | Departures | On time | Left on time | Cancelled | Typical arrival |
|---|---|---|---|---|---|
| Alaska Airlines | 10,751 | 83% | 85% | 0.8% | −7 min |
| Delta Air Lines | 6,044 | 88% | 89% | 0.6% | −12 min |
| Southwest Airlines | 5,342 | 81% | 78% | 0.3% | −6 min |
| United Airlines | 4,361 | 78% | 81% | 0.4% | −6 min |
| American Airlines | 2,235 | 79% | 78% | 1.2% | −8 min |
| Allegiant Air | 231 | 71% | 75% | 0.4% | −2 min |
| Frontier Airlines | 132 | 82% | 82% | 0.0% | −9 min |
Why flights are late at BOI
Airlines report a cause for every flight that arrives 15 or more minutes late. At BOI, 35% of delay minutes came from late-arriving aircraft: the plane showed up late from its previous flight, so the delay started somewhere else. Next is the airlines themselves at 34%. That's why the first flight of the morning is the safest bet: it has no earlier flight to inherit a delay from. Of the 178 cancellations, 44% were blamed on weather.
The average taxi from gate to takeoff is 17 minutes, about typical for a large U.S. airport.
Month by month
Over the latest 12 months 82% of BOI departures were on time, against 84% in the 12 months before, a decline of 2 points. The best recent month was February 2026 (88%); the worst, July 2026 (77%).
Worst cancellation days
The worst single day in the past year was Friday, Nov 21, 2025, when 11% of 87 scheduled departures were cancelled. Days like that are usually a major storm, a system outage or a holiday peak hitting bad weather. No average predicts them, so on a stormy forecast, check your airline's travel waivers.
| Date | Departures | Cancelled | On time |
|---|---|---|---|
| Nov 21, 2025 | 87 | 11% | 21% |
| Mar 13, 2026 | 84 | 8% | 63% |
| Mar 15, 2026 | 83 | 6% | 69% |
| Oct 24, 2025 | 87 | 6% | 78% |
| Nov 11, 2025 | 77 | 5% | 84% |
| Jan 26, 2026 | 79 | 5% | 90% |
| Jan 25, 2026 | 82 | 5% | 87% |
| Mar 7, 2026 | 69 | 4% | 83% |
| Nov 7, 2025 | 83 | 4% | 80% |
| Nov 20, 2025 | 84 | 4% | 82% |
Last flights of the day
The last flight of the day is a different bet. Across routes from BOI, each airline's final departure was cancelled 0.7% of the time, against 0.5% for its earlier flights (1.3× as often). Late in the day crews run short on duty hours, aircraft arrive late from elsewhere, and with no later flight to fold passengers into, cancelling is easier for the airline. 1.4% of last flights landed 3+ hours late. The riskiest last flight out was American Airlines to Dallas (3.6% cancelled).
| Last flight to | Airline | Leaves | Cancelled | 3h+ late | On time |
|---|---|---|---|---|---|
| DFW Dallas | American Airlines | 3:54 p.m. | 3.6% | 2.2% | 70% |
| ORD Chicago | United Airlines | 12:30 p.m. | 1.1% | 3.0% | 75% |
| SFO San Francisco | United Airlines | 7:05 p.m. | 0.3% | 3.0% | 57% |
| PHX Phoenix | American Airlines | 5:20 p.m. | 0.8% | 2.2% | 77% |
| GEG Spokane | Alaska Airlines | 9:23 p.m. | 1.9% | 0.8% | 76% |
| PHX Phoenix | Southwest Airlines | 5:40 p.m. | 0.6% | 2.0% | 66% |
| DEN Denver | United Airlines | 5:46 p.m. | 0.0% | 2.5% | 69% |
| PDX Portland | Alaska Airlines | 8:28 p.m. | 1.4% | 0.8% | 86% |
| DEN Denver | Southwest Airlines | 3:55 p.m. | 0.5% | 1.6% | 56% |
| SMF Sacramento | Southwest Airlines | 7:20 p.m. | 0.3% | 1.7% | 74% |
| SEA Seattle | Alaska Airlines | 8:47 p.m. | 1.1% | 0.8% | 65% |
| LAX Los Angeles | Delta Air Lines | 4:00 p.m. | 0.4% | 1.2% | 91% |
Each airline's last scheduled departure of the day on a route, on days it flies the route at least twice; past 12 months. Riskiest first.
Tips for flying out of BOI
- Book the earliest departure you can live with. At BOI the 6 a.m. flights do best.
- Traveling in July? Leave extra slack for anything that can't move: cruises, weddings, the last connection of the day.
- Choosing between airlines? Delta Air Lines has the better record here.
- Need to arrive tonight? Don't book the last flight out of BOI; the one before it leaves you a backup.
- Delayed already? Most delays at BOI come from late-arriving aircraft. If your inbound plane is late, your flight will be too, whatever the board says.
Routes from BOI
Where you're going matters too. From BOI, the most reliable busy route was to Portland (PDX, 90% on time) and the least reliable to San Francisco (SFO, 65%). Flights into congested airports inherit their delays: an air traffic program at the destination holds planes on the ground here.
Least reliable first. Routes with at least 365 flights a year.
| To | Flights | On time | Cancelled | Typical arrival |
|---|---|---|---|---|
| SFO San Francisco | 1,827 | 65% | 0.5% | 0 min |
| ORD Chicago | 1,111 | 74% | 1.2% | −4 min |
| SAN San Diego | 1,151 | 76% | 0.7% | −3 min |
| DFW Dallas | 817 | 79% | 2.8% | −9 min |
| SEA Seattle | 5,239 | 81% | 0.5% | −8 min |
| LAS Las Vegas | 1,440 | 81% | 0.6% | −6 min |
| DEN Denver | 3,034 | 81% | 0.1% | −7 min |
| SNA Santa Ana | 516 | 81% | 0.6% | −5 min |
| PHX Phoenix | 2,346 | 83% | 0.3% | −8 min |
| OAK Oakland | 529 | 83% | 0.0% | −7 min |
| ATL Atlanta | 548 | 84% | 1.3% | −11 min |
| GEG Spokane | 1,326 | 84% | 1.1% | −9 min |
| BUR Burbank | 499 | 85% | 0.4% | −8 min |
| MSP Minneapolis | 774 | 86% | 0.5% | −10 min |
| SMF Sacramento | 1,235 | 87% | 0.4% | −8 min |
| SJC San Jose | 687 | 87% | 0.1% | −8 min |
| SLC Salt Lake City | 1,732 | 90% | 1.0% | −12 min |
| LAX Los Angeles | 1,689 | 90% | 0.2% | −9 min |
| PDX Portland | 1,744 | 90% | 0.8% | −9 min |
Flights into BOI
Arriving rather than leaving? These are the routes into Boise /Gowen, least reliable first. The weakest is from Dallas (62% on time).
| From | Flights | On time | Cancelled |
|---|---|---|---|
| DFW Dallas | 817 | 62% | 2.7% |
| ORD Chicago | 1,108 | 68% | 1.5% |
| LAS Las Vegas | 1,439 | 72% | 0.6% |
| SFO San Francisco | 1,823 | 75% | 0.3% |
| DEN Denver | 3,038 | 76% | 0.1% |
| SAN San Diego | 1,153 | 79% | 0.4% |
| MSP Minneapolis | 774 | 80% | 0.5% |
| PHX Phoenix | 2,346 | 80% | 0.5% |
| ATL Atlanta | 548 | 81% | 1.3% |
| SJC San Jose | 689 | 82% | 0.3% |
| BUR Burbank | 498 | 83% | 0.6% |
| OAK Oakland | 530 | 83% | 0.0% |
| SMF Sacramento | 1,235 | 83% | 0.3% |
| SEA Seattle | 5,237 | 84% | 0.4% |
| SNA Santa Ana | 516 | 85% | 1.0% |
| SLC Salt Lake City | 1,732 | 86% | 0.8% |
| GEG Spokane | 1,326 | 87% | 1.6% |
| PDX Portland | 1,747 | 87% | 0.7% |
| LAX Los Angeles | 1,691 | 89% | 0.2% |
Questions about BOI delays
What is the best time to fly out of BOI?
Flights scheduled at 6 a.m.: over the past year 93% of BOI departures at that hour arrived on time, against 70% at 7 p.m., the worst hour.
What month has the most flight delays at BOI?
July (80% on time). October is the best month (87%).
Which airline is most on time at BOI?
Delta Air Lines: 88% of its BOI departures arrived on time over the past year. United Airlines had the weakest record at 78%.
Why are flights delayed at BOI?
The biggest cause was late-arriving aircraft (35% of delay minutes): the plane showed up late from its previous flight, so the delay started somewhere else. Then the airlines themselves (34%).
How often are flights cancelled at BOI?
0.6% of scheduled departures over the past 12 months, peaking in January at 1.0%.
Hours are scheduled local departure times. "On time" means arriving less than 15 minutes late at the destination; cancelled and diverted flights count as not on time. Method.