Best time to fly Chicago to Dallas

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

Best month

February

85.1% on time · 135 flights

Worst month

June

64.4% on time · 195 flights

Month Flights On time Cancelled When late, by
January 156 84.5% 5.13% 45 min
February 135 85.1% 0.74% 45 min
March 171 81.4% 1.75% 92 min
April 172 80.4% 2.33% 44 min
May 176 73.5% 1.7% 54 min
June 195 64.4% 2.56% 61 min
July 202 69.4% 2.48% 76 min
August 193 79.6% 0.52% 64 min
September 190 80.3% 0% 48 min
October 195 81.3% 1.03% 49 min
November 178 80.7% 6.74% 47 min
December 190 73.7% 0% 52 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.