Best time to fly Boston to San Antonio

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

There is not yet enough of the year on record for this route to say anything about seasons. The months below are shown as recorded.

Month Flights On time Cancelled When late, by
January 29 78.6% 3.45% 99 min
February 28 70.4% 3.57% 93 min
March 31 96.8% 0% 115 min
April 30 82.8% 3.33% 70 min
May 31 76.7% 3.23% 78 min
June 30 67.9% 6.67% 63 min
July 30 89.7% 0% 39 min
August 30 90% 0% 87 min
September 30 83.3% 0% 50 min
October 30 76.7% 0% 79 min
November 28 77.8% 3.57% 84 min
December 28 66.7% 3.57% 103 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.