Best time to fly San Francisco to New York

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

Best month

October

86.6% on time · 1,148 flights

Worst month

June

71.6% on time · 1,198 flights

Month Flights On time Cancelled When late, by
January 1,037 84.9% 3.18% 92 min
February 913 84.2% 4.38% 82 min
March 1,055 82.6% 0.57% 89 min
April 1,122 84.4% 0.18% 65 min
May 1,216 73.5% 0.33% 76 min
June 1,198 71.6% 1.17% 81 min
July 1,182 72% 2.62% 79 min
August 1,172 79.5% 1.54% 98 min
September 1,126 85.7% 0.18% 83 min
October 1,148 86.6% 0.35% 75 min
November 1,089 85.2% 0.55% 68 min
December 1,087 80.6% 1.29% 80 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.