{"chart":{"slug":"flight-delays-by-month","title":"Which months have the most flight delays?","takeaway":"In the 12 months from September 2025 to August 2026, flights were most often late in July 2026, when 28.3% arrived 15 or more minutes late, and least often in September 2025 (16.6%). Each bar is one month of the latest year of data, not an average over many years.","topic":"Air travel","chart_type":"bar","ranking":false,"x_label":"Month","y_label":"% of flights arriving 15+ minutes late","unit":"percent","points_count":12,"source":{"name":"U.S. Bureau of Transportation Statistics, Airline On-Time Performance (Reporting Carrier On-Time Performance, 1987–present)","url":"https://www.transtats.bts.gov/DL_SelectFields.aspx?gnoyr_VQ=FGJ\u0026QO_fu146_anzr=b0-gvzr"},"license":{"name":"Public domain (U.S. government work)","url":"https://www.usa.gov/government-copyright"},"data_as_of":"2026-08-31","updated_at":"2026-10-20T16:49:43.834Z","url":"https://chart.ly/charts/flight-delays-by-month","api_url":"https://chart.ly/api/v1/charts/flight-delays-by-month","csv_url":"https://chart.ly/charts/flight-delays-by-month/data.csv","image_url":"https://chart.ly/charts/flight-delays-by-month/image.png","embed_url":"https://chart.ly/charts/flight-delays-by-month/embed","credit":"U.S. Bureau of Transportation Statistics, Airline On-Time Performance (Reporting Carrier On-Time Performance, 1987–present), via Chartly (https://chart.ly/charts/flight-delays-by-month)","credit_html":"U.S. Bureau of Transportation Statistics, Airline On-Time Performance (Reporting Carrier On-Time Performance, 1987–present), via \u003ca href=\"https://chart.ly/charts/flight-delays-by-month\"\u003eChartly\u003c/a\u003e","average_label":null,"zero_axis":true,"data":[{"label":"Sep 2025","value":16.6},{"label":"Oct 2025","value":20.3},{"label":"Nov 2025","value":20.6},{"label":"Dec 2025","value":26.8},{"label":"Jan 2026","value":20.8},{"label":"Feb 2026","value":19.8},{"label":"Mar 2026","value":24.3},{"label":"Apr 2026","value":20.2},{"label":"May 2026","value":21.4},{"label":"Jun 2026","value":25.7},{"label":"Jul 2026","value":28.3},{"label":"Aug 2026","value":26.9}],"annotations":[]},"docs":"https://chart.ly/developers","terms":"Free to use with credit: wherever you show or quote a chart's data, name Chartly with a link to that chart's url (each chart's credit line does both) and credit its source as its license asks.","credit":"U.S. Bureau of Transportation Statistics, Airline On-Time Performance (Reporting Carrier On-Time Performance, 1987–present), via Chartly (https://chart.ly/charts/flight-delays-by-month)"}