Best time to fly San Antonio to Chicago

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

Best month

February

84.8% on time · 145 flights

Worst month

March

65.9% on time · 179 flights

Month Flights On time Cancelled When late, by
January 145 78.3% 3.45% 80 min
February 145 84.8% 0% 53 min
March 179 65.9% 3.91% 63 min
April 175 74.4% 2.86% 52 min
May 179 83.5% 1.12% 84 min
June 174 74.7% 4.02% 111 min
July 167 68.4% 2.99% 82 min
August 154 73.5% 3.25% 74 min
September 151 81.3% 0.66% 63 min
October 179 78.2% 0% 70 min
November 160 77.1% 3.75% 71 min
December 160 76.6% 1.25% 87 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.