Best time to fly Chicago to Peoria

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

Best month

September

80.7% on time · 313 flights

Worst month

December

61.7% on time · 282 flights

Month Flights On time Cancelled When late, by
January 309 70.9% 2.27% 70 min
February 287 69.1% 0.35% 68 min
March 332 66.9% 4.52% 68 min
April 500 75.2% 5.6% 85 min
May 401 77.5% 1.25% 78 min
June 396 71.9% 2.53% 69 min
July 305 64.9% 1.64% 62 min
August 291 71.6% 2.75% 80 min
September 313 80.7% 0.32% 51 min
October 316 77.2% 0% 52 min
November 256 71% 8.98% 71 min
December 282 61.7% 4.26% 72 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.