Best time to fly Springfield to Chicago

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

Best month

September

80.9% on time · 336 flights

Worst month

March

63% on time · 243 flights

Month Flights On time Cancelled When late, by
January 189 72.7% 2.12% 86 min
February 159 76.1% 2.52% 69 min
March 243 63% 2.06% 102 min
April 291 76.7% 1.37% 150 min
May 261 77.6% 0.77% 96 min
June 281 71% 3.91% 79 min
July 275 68.4% 0.73% 77 min
August 325 70.8% 1.54% 94 min
September 336 80.9% 0% 66 min
October 316 75.6% 0% 84 min
November 212 74% 3.77% 115 min
December 231 63.3% 2.16% 106 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.