Best time to fly Miami to San Francisco

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

Best month

March

86.1% on time · 154 flights

Worst month

May

56.1% on time · 164 flights

Month Flights On time Cancelled When late, by
January 153 74.1% 3.92% 120 min
February 137 77.4% 0% 55 min
March 154 86.1% 1.95% 75 min
April 153 57% 0% 54 min
May 164 56.1% 0% 53 min
June 174 56.4% 0.57% 60 min
July 155 71.2% 0.65% 57 min
August 142 70.9% 0.7% 65 min
September 91 78% 0% 63 min
October 122 82% 0% 44 min
November 143 81.8% 0% 60 min
December 137 77.4% 0% 96 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.