BUF to DEN flight delays
Buffalo, NY (BUF) Denver, CO (DEN) · 1,359 miles
600 flights · January 2025 – August 2026 · US Bureau of Transportation Statistics
76.79%
Arrived on time
Within 15 minutes of schedule
0.17%
Cancelled
Share of scheduled flights
59 min
When late, late by
Average across delayed arrivals
15 min
Delay per flight
Averaged over every flight flown
What the record says about this route
Which airline you fly changes the odds here. United Airlines arrived on time 12.6 points more often than Southwest Airlines over the same period on the same route — same airports, same weather, same air traffic control. A gap that survives all of that is about how the two airlines are run.
The season swings this route hard. In October it ran 25.6 points more punctual than in June — a difference bigger than the one between the best and worst airlines on most routes. If the date is flexible, it is worth more than the carrier.
The route has been getting worse. The later months run 9.6 points less punctual than the earlier ones. A drift of that size is rarely weather; it is more often an airline adding frequencies faster than the airports can absorb them.
The two directions do not behave alike. DEN to BUF arrives on time 9.9 points less often than the outbound. Delay accumulates through the flying day, so whichever direction is scheduled later tends to carry the worse record — which is an argument for booking the morning departure if the choice exists.
Which airline should you fly on this route?
Over January 2025 – August 2026, United Airlines arrived on time most often on BUF to DEN. Southwest Airlines was late most often. Flights ran closest to schedule in October and worst in June.
Every airline on BUF to DEN
Ranked by how many flights each one operated. A carrier with fewer than 100 flights in the period is listed but not graded.
| Airline | Flights | On time | Cancelled | Avg delay | Grade |
|---|---|---|---|---|---|
| United Airlines | 293 | 83.96% | 0% | 76 min | B |
| Southwest Airlines | 259 | 71.32% | 0.39% | 49 min | D |
| Frontier Airlines | 48 | 62.5% | 0% | 52 min | — |
Month by month
Share of flights that arrived within 15 minutes of schedule, by month flown.
The return leg
DEN to BUF Denver back to Buffalo 66.89% on time DCommon questions
Are flights from Buffalo to Denver usually delayed?
76.79% of flights on the BUF to DEN route arrived within 15 minutes of schedule, so roughly 2 in every ten arrived late. That is about the same as the average route in this record.
Which airline is most on time from Buffalo to Denver?
United Airlines, at 83.96% on time across 293 flights. The least punctual on the route was Southwest Airlines at 71.32%.
How often are BUF to DEN flights cancelled?
0.17% of scheduled flights did not operate — about 2 in every thousand. That is in the normal range.
What is the best month to fly Buffalo to Denver?
October, when 87.1% of flights arrived on time. The worst was June at 61.5%.
When BUF to DEN flights are late, how late are they?
About 59 minutes on average across the flights that arrived more than 15 minutes behind schedule.
What these figures do and do not tell you
Everything on this page is counted from the flights that actually operated on BUF to DEN during January 2025 – August 2026, as reported by the airlines to the US Bureau of Transportation Statistics. "On time" is the federal definition: arriving at the gate within 15 minutes of the scheduled time.
A route's record is a description of the past, not a forecast. Weather, air traffic control and the aircraft's earlier flights that day drive most delays, and none of them are predictable from a historical rate. What the record does tell you is whether this route runs late more often than others, and which carrier on it has the better history — which is the part you can actually act on when you book.
Cancellations are counted separately from delays because they are a different problem for a traveller: a late flight still gets you there. How the grade is calculated →