Best time to fly Chicago to Springfield

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

Best month

May

88.6% on time · 123 flights

Worst month

January

63.8% on time · 58 flights

Month Flights On time Cancelled When late, by
January 58 63.8% 0% 81 min
February 52 69.2% 0% 42 min
March 58 74.5% 10.34% 50 min
April 109 80% 3.67% 97 min
May 123 88.6% 0% 45 min
June 110 76.1% 0.91% 95 min
July 47 68.2% 6.38% 97 min
August 60 72.4% 3.33% 92 min
September 57 80.4% 1.75% 73 min
October 62 82.3% 0% 49 min
November 59 73.2% 5.08% 89 min
December 59 66.1% 5.08% 84 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.