Summer is delay season
June, July, and August consistently have the highest delay rates — around 22-25% of flights are delayed. The main culprits: afternoon thunderstorms (especially in the Southeast and Midwest) and peak passenger volumes that leave no slack in the system.
Winter: fewer delays, more cancellations
December through February have moderate delay rates but the highest cancellation rates. Winter storms can shut down entire airports for hours. The Northeast (JFK, EWR, BOS) and Midwest (ORD, DTW) are most affected.
The best months to fly: September and October. Summer crowds are gone, hurricane season is winding down, and winter storms haven't started.
💡 Planning ahead?
Book September or early October flights for the lowest delay risk. If you must fly in summer, book morning departures and avoid connecting through thunderstorm-prone hubs (ATL, ORD, DFW).