Best time to fly Portland to New York

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

Best month

November

96.6% on time · 58 flights

Worst month

August

71.1% on time · 206 flights

Month Flights On time Cancelled When late, by
January 30 80.8% 13.33% 122 min
February 28 76.9% 7.14% 55 min
March 12 90.9% 8.33% 93 min
April 91 78% 0% 67 min
May 100 81.6% 2% 87 min
June 108 73.1% 0% 98 min
July 185 72.3% 9.73% 134 min
August 206 71.1% 5.83% 85 min
September 171 85.4% 0% 105 min
October 159 81% 0.63% 81 min
November 58 96.6% 0% 26 min
December 51 80.4% 0% 43 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.