Best time to fly Dayton to Washington

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

Best month

September

85.1% on time · 171 flights

Worst month

February

58.3% on time · 180 flights

Month Flights On time Cancelled When late, by
January 180 68.3% 9.44% 137 min
February 180 58.3% 6.11% 106 min
March 198 70.2% 3.03% 129 min
April 192 72% 1.56% 65 min
May 198 67.9% 3.03% 72 min
June 163 79.6% 12.27% 90 min
July 159 77.8% 8.18% 146 min
August 160 77.6% 2.5% 125 min
September 171 85.1% 0.58% 81 min
October 180 81.1% 0% 75 min
November 184 81.6% 2.17% 86 min
December 150 68.3% 3.33% 127 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.