Best time to fly Colorado Springs to Chicago

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

Best month

September

87.8% on time · 150 flights

Worst month

February

72.6% on time · 84 flights

Month Flights On time Cancelled When late, by
January 104 74.5% 0.96% 112 min
February 84 72.6% 0% 99 min
March 95 72.8% 3.16% 187 min
April 145 81.8% 1.38% 202 min
May 156 87% 0.64% 62 min
June 176 76.2% 3.98% 104 min
July 155 77% 0.65% 64 min
August 155 84% 1.29% 80 min
September 150 87.8% 0.67% 81 min
October 155 83.9% 0% 57 min
November 147 81.9% 2.04% 111 min
December 149 77.9% 0% 153 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.