73% of flights from Buffalo to Denver arrived on time over the past 12 months. That is worse than the typical U.S. route. Most reliable airline: United Airlines (84%). 8% 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 BUF → DEN: when a flight was late, it was under 45 minutes late 64% of the time. About 1 in 14 flights landed an hour or more late, and 1 in 115 three hours or more; 0.2% were cancelled outright.
- On time or early73%
- 15–30 min late12%
- 30–60 min late7.2%
- 1–2 hours late4.7%
- 2–3 hours late1.6%
- 3+ hours late0.9%
- Diverted0.5%
- Cancelled0.2%
Share of all 573 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 | 293 | 84% | 0.0% | −4 min | 5.1% | +67 min | United Airlines |
| Southwest Airlines | 258 | 63% | 0.4% | +3 min | 9.3% | +50 min | Southwest Airlines |
| Frontier Airlines | 22 | — | — | — | — | — | 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 BUF). Delays build through the day as late planes knock on, so early flights usually do best.
By airline and hour
| Departs | United Airlines |
|---|---|
| 8 a.m. | 83% |
By month
Each calendar month pooled over 2023–2026. Best: October (87%). Worst: May (69%).
By day of week
| Day | Flights | On time | Cancelled |
|---|---|---|---|
| Monday | 85 | — | — |
| Tuesday | 66 | — | — |
| Wednesday | 63 | — | — |
| Thursday | 72 | — | — |
| Friday | 84 | — | — |
| Saturday | 110 | 68% | 0.0% |
| Sunday | 93 | — | — |
Why flights were late
Share of delay minutes on flights 15+ minutes late, as reported to BTS by the airlines.
Cancellations: weather 1
Month by month
Not enough months with data to draw a trend.
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 1727 | 9:00 a.m. | 293 | 84% | 0.0% | −4 min | United Airlines |
Worst days in the past year
| Date | Flights | On time | Cancelled |
|---|---|---|---|
| Nov 29, 2025 | 3 | 33% | 0 |
| Jul 26, 2026 | 3 | 33% | 0 |
| Aug 8, 2026 | 3 | 33% | 0 |
| Sep 12, 2025 | 3 | 33% | 0 |
| Jul 18, 2026 | 3 | 33% | 0 |
Questions
How often are flights from BUF to DEN on time?
73% of 573 scheduled flights from Buffalo, NY to Denver, CO arrived within 15 minutes of schedule between September 2025 and August 2026. 0.2% were cancelled.
Which airline is most on time from BUF to DEN?
United Airlines: 84% of its 293 flights on the route arrived on time. Southwest Airlines: 63%.
What month has the most delays from BUF to DEN?
May (69% on time). The best month is October (87%), over 2023–2026.
Related
- DEN → BUF (return)
- Buffalo Niagara (BUF) 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.