The best and worst months to fly
Flight delays aren’t spread evenly across the year. Here’s how on-time arrivals rise and fall month by month across U.S. airports, from public U.S. DOT data, 2000–2025.
Last reviewed June 21, 2026 · Data covers 2000–2025
The pattern
On-time arrivals by month of the year
Longer bars are better — a higher share of flights arriving within 15 minutes of schedule. The smoothest month is highlighted in green, the most delay-prone in red, combined across every U.S. airport and every year in the window.
The takeaway
Best and worst months to fly
Across the window we cover, September was the most reliable month for on-time arrivals (83%), while June was the most delay-prone (75%). Summer thunderstorms and winter weather are the usual culprits behind the worst stretches.
Based on 166,117,824 arriving flights, 2000–2025.
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