Best time to fly San Diego to San Francisco

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

Best month

January

81.5% on time · 1,028 flights

Worst month

June

53.3% on time · 1,196 flights

Month Flights On time Cancelled When late, by
January 1,028 81.5% 1.26% 82 min
February 897 74% 0.89% 68 min
March 1,031 75.6% 0.87% 57 min
April 1,046 65.3% 0.19% 51 min
May 1,137 61.4% 0.53% 59 min
June 1,196 53.3% 1.09% 55 min
July 1,122 68.3% 1.78% 62 min
August 1,161 73.3% 0.52% 52 min
September 1,155 71% 1.13% 49 min
October 1,240 63.4% 1.45% 56 min
November 1,151 65.7% 1.48% 70 min
December 1,080 65.3% 1.67% 77 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.