Best time to fly Washington to Cincinnati

Every month pooled across the years on record, so "July" means July generally rather than one particular July. Full IAD to CVG record →

Best month

January

100% on time · 6 flights

Worst month

June

74% on time · 78 flights

Month Flights On time Cancelled When late, by
January 6 100% 33.33%
February 41 90.2% 0% 36 min
March 80 82.3% 0% 78 min
April 81 93.8% 0% 50 min
May 77 85.5% 1.3% 77 min
June 78 74% 0% 68 min
July 61 88.3% 1.64% 50 min
August 108 84.5% 4.63% 77 min
September 80 95% 0% 85 min
October 89 86.5% 0% 66 min
November 115 83.9% 2.61% 57 min
December 103 80.6% 0% 83 min

What a seasonal pattern can and cannot tell you

Months differ for reasons that repeat — summer thunderstorms in the American interior, winter fog and de-icing in northern Europe, school holidays filling every seat and leaving no slack in the schedule. Those are real and they come back each year.

What the pattern cannot do is forecast a particular flight. A quiet month has late days and a bad month has punctual ones. Treat this as a way to choose between two dates you are indifferent about, not as a promise.