Best Time to Fly IAD to MIA: On-Time Stats by Hour & Airline
Washington Dulles International → Miami International
Data through July 2026 · Last updated October 18, 2026
625 flights were scheduled from Washington (IAD) to Miami (MIA) in the last 12 months, and 83.2% of those that flew arrived on time, 5.6 points above the US average of 77.6%.
United Airlines was the most punctual of the 2 airlines on the route at 86.2%, while Frontier Airlines trailed at 69.4%.
September has been the best month (92% on time) and Sunday the weakest day of the week (77%).
0.8% of flights were cancelled, versus 1.8% nationally.
IAD to MIA on-time performance by airline
Last 12 months. Airlines with fewer than 30 completed flights are marked “limited data”.
| Airline | On time | Avg delay when late | Cancelled | Flights |
|---|---|---|---|---|
| United Airlines | 86.2% | 65 min | 0.6% | 512 |
| Frontier Airlines | 69.4% | 67 min | 1.8% | 113 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly IAD to MIA
On-time arrival % by scheduled departure hour (local time), 1,186 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 8am–9am | 87.5% | 0.4% | 499 |
| 9am–10am | 89.6% | 0.9% | 213 |
| 10am–11am | Limited data | 2 | |
| 11am–12pm | Limited data | 3 | |
| 12pm–1pm | Limited data | 5 | |
| 1pm–2pm | 82.7% | 0.7% | 140 |
| 2pm–3pm | Limited data | 9 | |
| 3pm–4pm | 73.6% | 0.0% | 53 |
| 4pm–5pm | Limited data | 12 | |
| 5pm–6pm | 75.2% | 0.0% | 145 |
| 6pm–7pm | Limited data | 2 | |
| 7pm–8pm | 51.0% | 0.0% | 51 |
| 8pm–9pm | Limited data | 12 | |
| 9pm–10pm | Limited data | 30 | |
| 10pm–11pm | Limited data | 10 | |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on IAD to MIA
On-time arrivals during holiday periods compared with all other days, last 24 months.
| Period | On time | vs other days | Cancelled | Flights |
|---|---|---|---|---|
| Thanksgiving week (Tue before to Mon after) | Limited data | 24 | ||
| Christmas & New Year (Dec 20 - Jan 3) | 83.6% | -0.2 pts | 0.0% | 67 |
| Summer peak (Jun 15 - Aug 15) | 73.5% | -10.3 pts | 1.2% | 168 |
| All other days | 83.8% | — | 0.8% | 927 |
Monthly on-time trend
On-time arrival % each month, with the 12-month US average for reference.
What causes delays on this route
Share of reported delay minutes, last 12 months (BTS cause categories).