Best time to fly Boston to Raleigh/Durham

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

Best month

April

83.1% on time · 245 flights

Worst month

December

69.9% on time · 249 flights

Month Flights On time Cancelled When late, by
January 170 75.8% 10% 75 min
February 168 73.7% 7.14% 73 min
March 224 73.9% 2.68% 87 min
April 245 83.1% 0.41% 59 min
May 261 82.3% 0.38% 58 min
June 242 79.4% 3.72% 86 min
July 230 77% 1.74% 85 min
August 230 74.6% 0.87% 66 min
September 256 73.5% 1.17% 82 min
October 292 73.7% 2.4% 72 min
November 249 77.2% 1.2% 81 min
December 249 69.9% 1.2% 76 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.