Best time to fly New York to Washington

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

Best month

April

92.9% on time · 28 flights

Worst month

June

67.3% on time · 119 flights

Month Flights On time Cancelled When late, by
January 124 80.2% 6.45% 72 min
February 102 81.3% 5.88% 102 min
March 117 70.9% 11.97% 68 min
April 28 92.9% 0% 39 min
May 137 76.1% 2.19% 60 min
June 119 67.3% 7.56% 100 min
July 167 70.3% 7.19% 115 min
August 231 78.8% 7.79% 81 min
September 217 79.3% 1.84% 62 min
October 222 83.3% 0.45% 73 min
November 206 80.8% 6.31% 71 min
December 230 73.2% 2.61% 69 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.