Best time to fly Washington to Grand Rapids

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

Best month

September

79.7% on time · 120 flights

Worst month

February

54.3% on time · 94 flights

Month Flights On time Cancelled When late, by
January 94 72.3% 10.64% 87 min
February 94 54.3% 13.83% 80 min
March 115 68.9% 8.7% 77 min
April 119 60.9% 1.68% 67 min
May 125 68.6% 5.6% 69 min
June 119 55.6% 8.4% 103 min
July 119 69.2% 10.08% 111 min
August 119 75.7% 2.52% 80 min
September 120 79.7% 1.67% 92 min
October 142 78.9% 0% 61 min
November 109 70.3% 6.42% 57 min
December 113 58.3% 3.54% 85 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.