Best time to fly New York to Portland

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

Best month

February

87.8% on time · 54 flights

Worst month

October

64.5% on time · 142 flights

Month Flights On time Cancelled When late, by
January 61 83.9% 8.2% 64 min
February 54 87.8% 9.26% 79 min
March 83 71.4% 15.66% 49 min
April 134 75.9% 0.75% 57 min
May 130 82.9% 0.77% 41 min
June 123 84.2% 2.44% 89 min
July 81 66.2% 12.35% 75 min
August 86 86.9% 2.33% 50 min
September 86 87.1% 1.16% 69 min
October 142 64.5% 2.82% 59 min
November 81 73.7% 6.17% 77 min
December 76 70.8% 5.26% 66 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.