Best time to fly Chicago to Charleston

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

Best month

September

84.1% on time · 145 flights

Worst month

July

65.3% on time · 171 flights

Month Flights On time Cancelled When late, by
January 145 68.3% 4.14% 61 min
February 151 76.8% 0% 50 min
March 210 66.7% 4.29% 59 min
April 194 72.9% 2.58% 59 min
May 208 77.3% 0.48% 79 min
June 202 79.7% 2.48% 65 min
July 171 65.3% 1.75% 67 min
August 138 83.5% 3.62% 53 min
September 145 84.1% 0% 83 min
October 177 80.8% 0% 46 min
November 178 77.6% 4.49% 80 min
December 172 73.1% 0.58% 57 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.