Which months have the most flight delays?

In July 2026, 28.3% of U.S. flights arrived 15 or more minutes late, the most of the 12 months from August 2025, when summer thunderstorms meet full planes. September 2025 was the best month, at 16.6%. Each bar is one month of the latest year of data, not an average over many years.

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Source and date

Source: U.S. Bureau of Transportation Statistics, Airline On-Time Performance (Reporting Carrier On-Time Performance, 1987–present)
License: Public domain (U.S. government work)
Data as of: July 31, 2026
Published: September 25, 2026

The data

Month	% of flights arriving 15+ minutes late
Aug 2025	22.6
Sep 2025	16.6
Oct 2025	20.3
Nov 2025	20.6
Dec 2025	26.8
Jan 2026	20.8
Feb 2026	19.8
Mar 2026	24.3
Apr 2026	20.2
May 2026	21.4
Jun 2026	25.7
Jul 2026	28.3