Best time to fly Boston to New York

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

Best month

August

81.6% on time · 500 flights

Worst month

July

67.3% on time · 493 flights

Month Flights On time Cancelled When late, by
January 482 75.6% 8.92% 72 min
February 465 71.6% 9.25% 74 min
March 517 69.2% 2.13% 60 min
April 440 78.4% 0% 62 min
May 437 80.5% 1.6% 61 min
June 430 74% 5.35% 77 min
July 493 67.3% 10.14% 107 min
August 500 81.6% 1.2% 77 min
September 545 79.3% 2.57% 61 min
October 552 78.3% 3.26% 80 min
November 447 77.8% 6.49% 59 min
December 430 70.7% 3.95% 73 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.