Route profile
DEN→BOS
Flight reliability, delays and best times to fly from Denver to Boston, 1,754 miles.
Right now
Aviation weather is not currently a factor.
Aviation weather is not currently a factor.
Route reliability
July 2023 – July 2026
Better than 17% of comparable major US routes (4,598 compared)
Calculated from 11,791 flights. How this is calculated
DEN → BOS arrives on time 70.9% of the time; the return trip, BOS → DEN, arrives on time 78.2% of the time, a 7.2-point gap between the two directions of the same city pair.
DEN → BOS spends 27.1 minutes on the ground on a 1,754-mile trip: 19.5 minutes from pushback to wheels-up at DEN and 7.5 minutes from touchdown to gate at BOS.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What stands out
On-time performance swings unusually widely by time of day here, wider than 98% of 4,023 comparable routes.
86.9% on time for 5–9 AM departures, against 50.5% for 6–9 PM.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Ranked against every other route with the same kind of figure and at least 4,023 in the comparison.
Why DEN → BOS flights are cancelled
July 2023 – July 2026
DEN → BOS cancelled 125 of 11,791 scheduled flights — about 1 in every 94. The reason filed most often was extreme weather, 45.6% of the cancellations coded on this route — about 1 in every 207 scheduled flights.
Share of cancellations
Of 125 cancelled departures carrying a reason code.
What each reason means
Conditions the carrier judged severe enough to stop the flight: a blizzard, a hurricane, a line of thunderstorms.
57 cancellations, 45.6% of the total.
Crew, maintenance, aircraft cleaning, baggage or fueling: what BTS counts as within the carrier’s own control.
55 cancellations, 44.0% of the total.
Airport capacity, air traffic control flow programs, heavy traffic and ordinary bad weather. A system decision, not the airline’s.
13 cancellations, 10.4% of the total.
A terminal evacuation, a security breach, screening equipment failure, or screening queues over 29 minutes.
0 cancellations, 0.0% of the total.
Reason codes are the operating airline’s own filing with US DOT, not an independent finding of fault. Ordinary bad weather is filed under air traffic, so weather’s full share is larger than its bar.
125 coded cancellations were recorded on DEN → BOS; the section appears from 50.
When it goes wrong
July 2023 – July 2026
64 min late
against a median of 2 min early
DEN → BOS has an average that understates its risk: a typical arrival is 2 min early, but the worst tenth are 66 minutes worse than that. If the trip has something unmissable at the end of it, the median is the wrong number to plan against.
Percentiles over 11,791 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at BOS after arriving from DEN.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 45% | Likely to miss |
| 45 min | 28% | High risk |
| 60 min | 20% | High risk |
| 90 min | 11% | Some risk |
| 120 min | 6.1% | Some risk |
This is one leg of a connection. Gate changes and the next flight's own schedule matter too. And a connection can fail before delay is even the question — this route cancels 1.06% of the time and diverts 0.31% of the time, which a late arrival never shows up in.
Chance of missing is the share of 11,630 arrivals on this route that landed later than the connection time less 30 minutes to reach the next gate.
The worst tenth of arrivals on this route land at least 64 minutes late (90th-percentile gate arrival delay), over 11,791 operations.
Any other layover length: connection checker.
Best time to fly
DEN → BOS flights departing 5–9 AM arrived on time 86.9% of the time, against 50.5% for 6–9 PM departures, a gap of 36.4 percentage points.
By departure window
By departure hour
- 12 AM to 6 AM: too few flights to score
- 7 AM: 91.2% on time from 421 flights
- 8 AM: 84.4% on time from 892 flights
- 9 AM: 75.7% on time from 1,372 flights
- 10 AM: 69.2% on time from 377 flights
- 11 AM: 72.1% on time from 1,511 flights
- 12 PM: 62.2% on time from 307 flights
- 1 PM: 66.8% on time from 1,247 flights
- 2 PM: 61.6% on time from 615 flights
- 3 PM: 60.3% on time from 392 flights
- 4 PM: 65.6% on time from 536 flights
- 5 PM: 65.8% on time from 1,492 flights
- 6 PM: 49.3% on time from 384 flights
- 7 PM: 52.2% on time from 292 flights
- 8 PM to 9 PM: too few flights to score
- 10 PM: 69.8% on time from 224 flights
- 11 PM: 78.7% on time from 1,575 flights
Why DEN → BOS runs late
July 2023 – July 2026
the inbound aircraft was late, so this flight started late
airspace and airport capacity, including weather-driven flow control
crew, maintenance, boarding and fueling, all within the carrier’s control
weather severe enough to stop this flight specifically
screening or terminal security incidents
Share of the delay minutes US DOT attributed to each cause for DEN → BOS. Only delays of 15 minutes or more are attributed.
Late-arriving aircraft is the largest cause on DEN → BOS, at 38.3%: flights here mostly leave late because the plane came in late, and the day shows it: 5–9 AM departures arrived on time 86.9% of the time and 6–9 PM departures 50.5%.
How this route holds up in bad weather
July 2023 – July 2026
Bad weather raises cancellations by a similar amount at both ends of DEN to BOS: 4.0 times the normal rate at DEN and 3.9 times at BOS. Cancelled in bad weather against normal hours: DEN 2.8% against 0.7%, BOS 5.3% against 1.4%. Flights that did leave DEN in bad weather arrived on time 51.5% of the time, against 78.8% in normal hours.
Bad weather and normal hours at the airports
Scheduled departures, July 2023 – July 2026| Departures from | DEN | BOS |
|---|---|---|
| Cancelled in bad weather | 2.8% | 5.3% |
| Cancelled in normal hours | 0.7% | 1.4% |
| Arrived on time, bad weather | 51.5% | 65.1% |
| Arrived on time, normal hours | 78.8% | 79.7% |
| Departures in bad weather | 92,610 | 60,840 |
United Airlines (1.5% cancelled against 3.5% for the other carriers at DEN), Delta Air Lines (1.1% cancelled against 2.9% for the other carriers at DEN) and Southwest Airlines (2.4% cancelled against 3.1% for the other carriers at DEN) cancelled fewer departures from DEN in bad weather than the other carriers there did in the same months. None of the route’s other carriers was clearly worse. One more carrier flies this route but has too few bad-weather departures from DEN to compare.
This route’s airlines in bad weather at DEN
All departures from DEN| Airline | Bad-weather departures | Cancelled | Other carriers |
|---|---|---|---|
| United Airlines | 30,853 | 1.5%below the others | 3.5% |
| Delta Air Lines | 3,460 | 1.1%below the others | 2.9% |
| Southwest Airlines | 28,467 | 2.4%below the others | 3.1% |
These are airport figures, not route figures: every scheduled departure from DEN and BOS, to any destination, in hours the weather report called bad. The airline rows count each carrier’s departures from DEN on every route.
Weather source and limits. In full: DEN (airlines), BOS, What Weather Costs Each Airport, Who Cancels More When the Weather Turns, Airports That Change Places When Weather Turns.
Airlines on this route
Carriers with at least 200 flights, by the airline that operated each one.
| Carrier | Flights | On time | Cancelled | Median delay | Severe |
|---|---|---|---|---|---|
| United Airlines | 5,956 | 76.5% | 1.01% | -6 min | 9.4% |
| Southwest Airlines | 2,626 | 60.7% | 0.65% | 7 min | 13.1% |
| JetBlue | 1,944 | 64.7% | 1.65% | -1 min | 16.9% |
| Delta Air Lines | 1,265 | 75.6% | 1.26% | -3 min | 7.6% |
United Airlines flew 50.5% of the 11,791 flights listed.
United Airlines arrived on time 15.8 percentage points more often than Southwest Airlines on this route.
Flights on this route
Flight numbers with at least 600 operations here and still on the schedule.
Weekly and seasonal patterns
By day of week
Saturday is historically the most reliable day and Thursday the least, a gap of 8.0 percentage points.
By month
- Jan: 76.8%
- Feb: 74.0%
- Mar: 74.3%
- Apr: 77.2%
- May: 66.9%
- Jun: 67.3%
- Jul: 62.7%
- Aug: 67.0%
- Sep: 61.7%
- Oct: 73.8%
- Nov: 80.9%
- Dec: 80.1%
September is historically the weakest month and November the strongest, a spread of 19.2 percentage points.
Reliability over time
July 2023 – July 2026
- July 2023: 52.3% from 345 flights
- August 2023: 65.8% from 358 flights
- September 2023: 59.2% from 316 flights
- October 2023: 76.6% from 317 flights
- November 2023: 87.3% from 253 flights
- December 2023: 74.3% from 274 flights
- January 2024: 62.4% from 247 flights
- February 2024: 65.8% from 223 flights
- March 2024: 68.4% from 259 flights
- April 2024: 74.7% from 257 flights
- May 2024: 64.1% from 314 flights
- June 2024: 67.6% from 368 flights
- July 2024: 70.9% from 388 flights
- August 2024: 62.2% from 411 flights
- September 2024: 73.7% from 354 flights
- October 2024: 84.8% from 362 flights
- November 2024: 76.4% from 310 flights
- December 2024: 79.7% from 304 flights
- January 2025: 81.1% from 275 flights
- February 2025: 79.1% from 250 flights
- March 2025: 79.3% from 305 flights
- April 2025: 83.3% from 287 flights
- May 2025: 60.8% from 333 flights
- June 2025: 68.0% from 382 flights
- July 2025: 66.1% from 427 flights
- August 2025: 72.9% from 397 flights
- September 2025: 51.4% from 333 flights
- October 2025: 59.6% from 343 flights
- November 2025: 80.1% from 292 flights
- December 2025: 85.7% from 303 flights
- January 2026: 85.4% from 260 flights
- February 2026: 76.1% from 267 flights
- March 2026: 74.2% from 300 flights
- April 2026: 73.2% from 284 flights
- May 2026: 75.8% from 323 flights
- June 2026: 66.4% from 374 flights
- July 2026: 60.2% from 396 flights
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 70.9% against 73.7% in the 12 months before — declining by 2.8 percentage points.
Data and methodology
Calculated by FlyerIntel from 11,791 DEN → BOS flight records from the US DOT Bureau of Transportation Statistics, covering July 2023 – July 2026. Late means 15 or more minutes past scheduled arrival; cancelled and diverted flights are left out of on-time rates.
Full methodology · Data sources · Report a problem
Related research: How Long a Layover Needs to Be · Two Airlines on One Route · Best Time of Day to Fly From Major US Airports
Analysis last recomputed