Best time to fly Grand Rapids to Washington

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

Best month

September

85.5% on time · 120 flights

Worst month

February

53.7% on time · 93 flights

Month Flights On time Cancelled When late, by
January 95 60.5% 14.74% 76 min
February 93 53.7% 11.83% 117 min
March 115 72.5% 4.35% 160 min
April 119 78.6% 1.68% 87 min
May 125 73% 2.4% 75 min
June 120 60.5% 4.17% 172 min
July 119 73.5% 12.61% 131 min
August 119 79.6% 4.2% 93 min
September 120 85.5% 2.5% 200 min
October 141 79.3% 0.71% 80 min
November 109 71.7% 2.75% 88 min
December 112 57.4% 3.57% 94 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.