Route profile
MIA→SJU
Flight reliability, delays and best times to fly from Miami to San Juan, 1,045 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 38% of comparable major US routes (4,598 compared)
Calculated from 8,488 flights. How this is calculated
MIA → SJU arrives on time 76.1% of the time; the return trip, SJU → MIA, arrives on time 76.7% of the time.
MIA → SJU spends 26.5 minutes on the ground on a 1,045-mile trip: 19.9 minutes from pushback to wheels-up at MIA and 6.6 minutes from touchdown to gate at SJU.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What sets this route apart
Where MIA to SJU differs most from similar routes by hour, weekday, month and airline, July 2023 – July 2026.
MIA to SJU struggles most at 12 PM: 68.9% of its flights scheduled then arrive on time, 9.4 points behind the 78.3% on routes of similar length at the same hour. Against all other routes the gap is 10.6 points.
MIA to SJU is at its best against routes of similar length for flights scheduled at 4 PM: 72.2% arrive on time, 4.6 points ahead of the 67.6% those routes manage at that hour.
Saturday is the day MIA to SJU slips furthest against routes of similar length, 71.8% on time where they average 77.1%, 5.3 points lower. Against all other routes the gap is 7.3 points.
May is kinder to MIA to SJU than to routes of similar length: 80.4% on time against 74.1%, 6.3 points better. Against all other routes the gap is 5.2 points.
In January, MIA to SJU runs 5.6 points below routes of similar length, 71.3% on time to 76.9%. Against all other routes the gap is 7.8 points.
MIA to SJU against comparable routes
July 2023 – July 2026| Measure | This route | Compared with | Them | Gap | Flights behind it |
|---|---|---|---|---|---|
| Hour: 12 PM departures | 68.9% | routes of similar length | 78.3% | −9.4 pts | 922 here, 168,953 there |
| Hour: 4 PM departures | 72.2% | routes of similar length | 67.6% | +4.6 pts | 436 here, 154,484 there |
| Weekday: Saturday | 71.8% | routes of similar length | 77.1% | −5.3 pts | 1,188 here, 385,950 there |
| Month: May | 80.4% | routes of similar length | 74.1% | +6.3 pts | 700 here, 239,532 there |
| Month: January | 71.3% | routes of similar length | 76.9% | −5.6 pts | 698 here, 222,338 there |
Each comparison pools the flights of other routes, with this route’s own left out. Similar length means within 15% of this route’s 1,045 miles, with at least 5 such routes. A bucket is set against the most comparable group that has enough flights: similar length, then the same origin (at least 3 routes), then all other routes. Hours, weekdays and months appear only where both sides have 120 completed flights, and airlines where both have 600. The gap must be at least 2 points and 2 standard errors, and only the largest gap each way is kept per measure. These are differences in the flights counted, not causes.
Why MIA → SJU flights are cancelled
July 2023 – July 2026
MIA → SJU cancelled 67 of 8,488 scheduled flights — about 1 in every 127. The reason filed most often was extreme weather, 52.2% of the cancellations coded on this route — about 1 in every 243 scheduled flights.
Share of cancellations
Of 67 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.
35 cancellations, 52.2% of the total.
Crew, maintenance, aircraft cleaning, baggage or fueling: what BTS counts as within the carrier’s own control.
22 cancellations, 32.8% of the total.
Airport capacity, air traffic control flow programs, heavy traffic and ordinary bad weather. A system decision, not the airline’s.
10 cancellations, 14.9% 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.
67 coded cancellations were recorded on MIA → SJU; the section appears from 50.
When it goes wrong
July 2023 – July 2026
54 min late
against a median of 6 min early
MIA → SJU has an average that understates its risk: a typical arrival is 6 min early, but the worst tenth are 60 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 8,488 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at SJU after arriving from MIA.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 39% | Likely to miss |
| 45 min | 23% | High risk |
| 60 min | 16% | High risk |
| 90 min | 9.0% | Some risk |
| 120 min | 5.6% | 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 0.79% of the time and diverts 0.12% of the time, which a late arrival never shows up in.
Chance of missing is the share of 8,411 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 54 minutes late (90th-percentile gate arrival delay), over 8,488 operations.
Any other layover length: connection checker.
Best time to fly
MIA → SJU flights departing 5–9 AM arrived on time 89.3% of the time, against 64.2% for 9 PM–5 AM departures, a gap of 25.1 percentage points.
By departure window
By departure hour
- 12 AM to 4 AM: too few flights to score
- 5 AM: 83.8% on time from 156 flights
- 6 AM: 88.0% on time from 413 flights
- 7 AM: 91.4% on time from 480 flights
- 8 AM: 89.5% on time from 1,188 flights
- 9 AM: 83.2% on time from 367 flights
- 10 AM: 81.0% on time from 860 flights
- 11 AM: 74.8% on time from 249 flights
- 12 PM: 68.9% on time from 928 flights
- 1 PM: 71.5% on time from 598 flights
- 2 PM: 68.0% on time from 494 flights
- 3 PM: 68.9% on time from 453 flights
- 4 PM: 72.2% on time from 442 flights
- 5 PM: 67.0% on time from 233 flights
- 6 PM: 67.5% on time from 744 flights
- 7 PM: 65.3% on time from 218 flights
- 8 PM: 68.6% on time from 177 flights
- 9 PM: 63.1% on time from 230 flights
- 10 PM to 11 PM: too few flights to score
Why MIA → SJU runs late
July 2023 – July 2026
the inbound aircraft was late, so this flight started late
crew, maintenance, boarding and fueling, all within the carrier’s control
airspace and airport capacity, including weather-driven flow 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 MIA → SJU. Only delays of 15 minutes or more are attributed.
Late-arriving aircraft is the largest cause on MIA → SJU, at 42.6%: flights here mostly leave late because the plane came in late, and the day shows it: 5–9 AM departures arrived on time 89.3% of the time and 9 PM–5 AM departures 64.2%.
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 |
|---|---|---|---|---|---|
| American Airlines | 6,047 | 76.3% | 0.40% | -6 min | 8.3% |
| Frontier Airlines | 1,500 | 76.6% | 1.80% | -7 min | 11.0% |
| Spirit Airlines | 916 | 73.2% | 1.75% | -5 min | 12.2% |
American Airlines flew 71.5% of the 8,463 flights listed. Frontier Airlines cancelled 1.80% of its flights here against 0.40% for American Airlines.
Frontier Airlines arrived on time 3.4 percentage points more often than Spirit Airlines on this route.
Flights on this route
Flight numbers with at least 600 operations here and still on the schedule.
| Flight | Scheduled | Operations | On time |
|---|---|---|---|
| F92284 Frontier Airlines | 6:00 AM | 727 | 83.0% |
Weekly and seasonal patterns
By day of week
Wednesday is historically the most reliable day and Sunday the least, a gap of 10.6 percentage points.
By month
- Jan: 71.3%
- Feb: 80.4%
- Mar: 70.8%
- Apr: 77.3%
- May: 80.4%
- Jun: 75.0%
- Jul: 69.7%
- Aug: 69.5%
- Sep: 83.7%
- Oct: 85.2%
- Nov: 79.8%
- Dec: 75.7%
August is historically the weakest month and October the strongest, a spread of 15.7 percentage points.
Reliability over time
July 2023 – July 2026
- July 2023: 66.4% from 245 flights
- August 2023: 73.6% from 232 flights
- September 2023: 83.9% from 186 flights
- October 2023: 90.1% from 212 flights
- November 2023: 82.2% from 213 flights
- December 2023: 75.9% from 232 flights
- January 2024: 70.1% from 221 flights
- February 2024: 80.1% from 208 flights
- March 2024: 68.8% from 244 flights
- April 2024: 79.3% from 267 flights
- May 2024: 75.2% from 280 flights
- June 2024: 65.7% from 260 flights
- July 2024: 75.4% from 285 flights
- August 2024: 66.4% from 278 flights
- September 2024: 87.3% from 221 flights
- October 2024: 90.2% from 219 flights
- November 2024: 80.7% from 234 flights
- December 2024: 70.7% from 246 flights
- January 2025: 72.6% from 242 flights
- February 2025: 85.0% from 227 flights
- March 2025: 75.7% from 246 flights
- April 2025: 80.1% from 221 flights
- May 2025: 82.2% from 209 flights
- June 2025: 76.2% from 207 flights
- July 2025: 62.6% from 215 flights
- August 2025: 68.9% from 210 flights
- September 2025: 78.6% from 168 flights
- October 2025: 73.3% from 176 flights
- November 2025: 76.3% from 212 flights
- December 2025: 80.4% from 257 flights
- January 2026: 71.2% from 250 flights
- February 2026: 75.8% from 208 flights
- March 2026: 68.2% from 278 flights
- April 2026: 72.3% from 234 flights
- May 2026: 85.5% from 214 flights
- June 2026: 84.6% from 214 flights
- July 2026: 72.8% from 217 flights
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 75.5% against 77.2% in the 12 months before — declining by 1.7 percentage points.
Data and methodology
Calculated by FlyerIntel from 8,488 MIA → SJU 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