Best time to fly Chicago to Manhattan/Ft. Riley

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

Best month

May

82.4% on time · 120 flights

Worst month

December

51.7% on time · 60 flights

Month Flights On time Cancelled When late, by
January 36 52.9% 5.56% 239 min
February 45 71.1% 0% 59 min
March 62 65% 3.23% 73 min
April 114 73.4% 3.51% 55 min
May 120 82.4% 0.83% 60 min
June 92 65.2% 3.26% 123 min
July 61 53.4% 4.92% 75 min
August 38 69.4% 5.26% 59 min
September 30 66.7% 0% 55 min
October 56 53.6% 0% 116 min
November 59 75.5% 10.17% 51 min
December 60 51.7% 3.33% 162 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.