Best time to fly Chicago to Salt Lake City

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

Best month

September

81.4% on time · 501 flights

Worst month

July

64.3% on time · 498 flights

Month Flights On time Cancelled When late, by
January 478 71.4% 0.42% 65 min
February 531 73.6% 0.38% 77 min
March 637 70.1% 1.1% 92 min
April 531 73.4% 1.13% 92 min
May 555 77.6% 0.18% 70 min
June 556 64.8% 1.08% 71 min
July 498 64.3% 2.81% 80 min
August 502 68.2% 1.2% 77 min
September 501 81.4% 0.2% 70 min
October 533 81.4% 0.19% 55 min
November 463 78.7% 1.51% 96 min
December 501 68.9% 0.4% 79 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.