Best time to fly Portland to Atlanta

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

Best month

April

93.8% on time · 64 flights

Worst month

July

65.8% on time · 154 flights

Month Flights On time Cancelled When late, by
January 62 85% 3.23% 54 min
February 56 80% 0% 43 min
March 62 88.7% 0% 60 min
April 64 93.8% 0% 245 min
May 110 74.3% 0% 44 min
June 167 72.2% 2.4% 87 min
July 154 65.8% 4.55% 95 min
August 137 82.4% 0.73% 43 min
September 121 88.4% 0% 82 min
October 117 90.6% 0% 81 min
November 89 84.1% 1.12% 43 min
December 64 75% 0% 62 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.