Best time to fly Raleigh/Durham to Boston

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

Best month

March

86.5% on time · 468 flights

Worst month

September

72.5% on time · 543 flights

Month Flights On time Cancelled When late, by
January 388 83% 4.38% 93 min
February 365 83.5% 5.48% 64 min
March 468 86.5% 2.14% 104 min
April 487 84.9% 0.41% 66 min
May 517 79.4% 0.39% 73 min
June 480 78.5% 2.29% 79 min
July 498 74.3% 2.21% 96 min
August 535 79.6% 2.06% 122 min
September 543 72.5% 0.74% 80 min
October 585 79.1% 1.2% 75 min
November 507 86.5% 0.59% 76 min
December 512 79.3% 1.76% 74 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.