81% of flights from Boise to Denver arrived on time over the past 12 months. That is about the typical U.S. route. The 5 a.m. departures ran on time 93% of the time; the 4 p.m. ones 33%. Most reliable airline: United Airlines (83%). 7% of flights arrived more than an hour late or not at all.
How late?
The on-time rate treats a flight 20 minutes late the same as one 5 hours late. Here's the split for BOI → DEN: when a flight was late, it was under 45 minutes late 56% of the time. About 1 in 15 flights landed an hour or more late, and 1 in 59 three hours or more; 0.1% were cancelled outright.
- On time or early81%
- 15–30 min late7.2%
- 30–60 min late4.4%
- 1–2 hours late3.6%
- 2–3 hours late1.4%
- 3+ hours late1.7%
- Diverted0.4%
- Cancelled0.1%
Share of all 3,034 scheduled flights, past 12 months, by arrival time against schedule.
By airline
| Airline | Flights | On time | Cancelled | Typical arrival | 1h+ late | Avg when late | Operated by |
|---|---|---|---|---|---|---|---|
| United Airlines | 1,814 | 83% | 0.1% | −8 min | 7.0% | +99 min | United Airlines 51%, SkyWest 49% |
| Southwest Airlines | 1,088 | 78% | 0.2% | −4 min | 6.0% | +58 min | Southwest Airlines |
| Frontier Airlines | 132 | 82% | 0.0% | −9 min | 7.6% | +101 min | Frontier Airlines |
Airline = the name on the ticket. Regional flights (e.g. "Delta Connection") count under the ticketing airline, and the operator is listed.
Best time of day to fly
On-time rate by scheduled departure hour (local time at BOI). Delays build through the day as late planes knock on, so early flights usually do best.
By airline and hour
| Departs | United Airlines | Southwest Airlines |
|---|---|---|
| 5 a.m. | 91% | 99% |
| 6 a.m. | 91% | — |
| 7 a.m. | — | 93% |
| 10 a.m. | 90% | 89% |
| 11 a.m. | — | 85% |
| 2 p.m. | 75% | — |
| 4 p.m. | — | 33% |
| 5 p.m. | 69% | — |
Last flight of the day
On BOI → DEN, each airline's last flight of the day was cancelled 0.3% of the time, against 0.1% for its earlier flights (3.0× as often). It arrived 3+ hours late 2.1% of the time (earlier flights: 1.6%). It matters more than the numbers suggest. Miss an earlier flight and there's another one that evening; miss the last one and you're usually waiting until morning.
| Airline | Last departure | Last: cancelled | Last: 3h+ late | Earlier: cancelled | Next morning |
|---|---|---|---|---|---|
| United Airlines | 5:46 p.m. | 0.0% | 2.5% | 0.1% | first flight 5:00 a.m. |
| Southwest Airlines | 3:55 p.m. | 0.5% | 1.6% | 0.0% | first flight 7:40 a.m. |
Last flight = the airline's last scheduled departure on this route that day, on days it flies the route at least twice; past 12 months. Times are typical scheduled times over the latest three months.
If you need to be in DEN tonight, book an earlier flight so there's a backup if it's cancelled.
By month
Each calendar month pooled over 2023–2026. Best: October (88%). Worst: June (76%).
By day of week
| Day | Flights | On time | Cancelled |
|---|---|---|---|
| Monday | 431 | 82% | 0.0% |
| Tuesday | 429 | 85% | 0.5% |
| Wednesday | 415 | 84% | 0.0% |
| Thursday | 455 | 79% | 0.2% |
| Friday | 431 | 73% | 0.2% |
| Saturday | 404 | 85% | 0.0% |
| Sunday | 469 | 81% | 0.0% |
Why flights were late
Share of delay minutes on flights 15+ minutes late, as reported to BTS by the airlines.
Cancellations: airline 3 · air traffic/airport 1
Month by month
Flight numbers on this route
Regular flights with at least 120 scheduled trips in the past year. Sorted by departure time.
| Flight | Departs | Flights | On time | Cancelled | Typical arrival | Operated by |
|---|---|---|---|---|---|---|
| UA 5924 | 5:00 a.m. | 268 | 91% | 0.0% | −17 min | SkyWest |
| UA 1782 | 6:30 a.m. | 364 | 90% | 0.3% | −12 min | United Airlines |
| UA 6041 | 10:35 a.m. | 145 | 91% | 0.0% | −11 min | SkyWest |
| F9 3934 | 1:24 p.m. | 131 | 82% | 0.0% | −9 min | Frontier Airlines |
| UA 2173 | 2:40 p.m. | 364 | 75% | 0.3% | −4 min | United Airlines |
Worst days in the past year
| Date | Flights | On time | Cancelled |
|---|---|---|---|
| Mar 6, 2026 | 8 | 25% | 1 |
| Dec 19, 2025 | 8 | 25% | 0 |
| Aug 13, 2026 | 9 | 33% | 0 |
| Nov 30, 2025 | 9 | 33% | 0 |
| Mar 12, 2026 | 9 | 33% | 0 |
Questions
How often are flights from BOI to DEN on time?
81% of 3,034 scheduled flights from Boise, ID to Denver, CO arrived within 15 minutes of schedule between September 2025 and August 2026. 0.1% were cancelled.
What is the best time of day to fly BOI to DEN?
Flights scheduled to leave at 5 a.m. were the most reliable (93% on time). The 4 p.m. departures were the least (33%).
Which airline is most on time from BOI to DEN?
United Airlines: 83% of its 1,814 flights on the route arrived on time. Southwest Airlines: 78%. Frontier Airlines: 82%.
What month has the most delays from BOI to DEN?
June (76% on time). The best month is October (88%), over 2023–2026.
Is the last flight of the day from BOI to DEN more likely to be cancelled?
Yes. Each airline's last BOI–DEN flight of the day was cancelled 0.3% of the time over the past year, against 0.1% for its earlier flights. If the last flight is cancelled, the next one is usually the following morning.
Related
- DEN → BOI (return)
- Boise /Gowen (BOI) delays by hour
- Flights into Denver (DEN)
- United Airlines on-time record
- Southwest Airlines on-time record
- Frontier Airlines on-time record
- Connecting off this flight? Check the risk
Domestic flights by the airlines that report to the U.S. DOT, plus their regional partners. "On time" means arriving less than 15 minutes after schedule; cancelled and diverted flights count as not on time. Past performance is a guide, not a forecast. Method.