Best time to fly Detroit to Washington

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

Best month

September

83.2% on time · 247 flights

Worst month

February

58% on time · 239 flights

Month Flights On time Cancelled When late, by
January 249 59.2% 10.04% 54 min
February 239 58% 4.6% 77 min
March 271 63.3% 6.64% 111 min
April 262 71.4% 1.15% 58 min
May 257 75% 1.56% 74 min
June 232 68.6% 5.17% 84 min
July 239 61.1% 8.79% 112 min
August 233 78.9% 1.72% 60 min
September 247 83.2% 0% 68 min
October 258 81.4% 0% 96 min
November 253 58.1% 2.77% 83 min
December 238 61.8% 4.2% 84 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.