Best time to fly Baltimore to San Francisco

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

Best month

October

86.4% on time · 154 flights

Worst month

June

60.4% on time · 193 flights

Month Flights On time Cancelled When late, by
January 118 84.8% 5.08% 53 min
February 106 76.7% 0.94% 41 min
March 123 84.3% 1.63% 100 min
April 141 73% 0% 56 min
May 154 71.2% 0% 66 min
June 193 60.4% 0.52% 57 min
July 169 72.5% 1.18% 78 min
August 153 76.8% 1.31% 45 min
September 133 82.7% 0% 43 min
October 154 86.4% 0% 48 min
November 128 84.4% 0% 51 min
December 119 72.4% 0.84% 43 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.